diff --git a/lib/fluent/plugin/parser_msgpack.rb b/lib/fluent/plugin/parser_msgpack.rb
index b35f04b9f6..4d29bc6b7e 100644
--- a/lib/fluent/plugin/parser_msgpack.rb
+++ b/lib/fluent/plugin/parser_msgpack.rb
@@ -31,9 +31,9 @@ def parser_type
         :binary
       end
 
-      def parse(data)
+      def parse(data, &block)
         @unpacker.feed_each(data) do |obj|
-          yield convert_values(parse_time(obj), obj)
+          parse_unpacked_data(obj, &block)
         end
       end
       alias parse_partial_data parse
@@ -41,8 +41,29 @@ def parse(data)
       def parse_io(io, &block)
         u = Fluent::MessagePackFactory.engine_factory.unpacker(io)
         u.each do |obj|
-          time, record = convert_values(parse_time(obj), obj)
+          parse_unpacked_data(obj, &block)
+        end
+      end
+
+      def parse_unpacked_data(data)
+        if data.is_a?(Hash)
+          time, record = convert_values(parse_time(data), data)
           yield time, record
+          return
+        end
+
+        unless data.is_a?(Array)
+          yield nil, nil
+          return
+        end
+
+        data.each do |record|
+          unless record.is_a?(Hash)
+            yield nil, nil
+            next
+          end
+          time, converted_record = convert_values(parse_time(record), record)
+          yield time, converted_record
         end
       end
     end
diff --git a/test/plugin/test_parser_msgpack.rb b/test/plugin/test_parser_msgpack.rb
new file mode 100644
index 0000000000..eafea1538c
--- /dev/null
+++ b/test/plugin/test_parser_msgpack.rb
@@ -0,0 +1,127 @@
+require_relative '../helper'
+require 'fluent/test/driver/parser'
+require 'fluent/plugin/parser_msgpack'
+
+class MessagePackParserTest < ::Test::Unit::TestCase
+  def setup
+    Fluent::Test.setup
+  end
+
+  def create_driver(conf)
+    Fluent::Test::Driver::Parser.new(Fluent::Plugin::MessagePackParser).configure(conf)
+  end
+
+  sub_test_case "simple setting" do
+    data(
+      "Normal Hash",
+      {
+        input: "\x82\xA7message\xADHello msgpack\xA3numd",
+        expected: [{"message" => "Hello msgpack", "num" => 100}]
+      },
+      keep: true
+    )
+    data(
+      "Array of multiple Hash",
+      {
+        input: "\x92\x81\xA7message\xA3foo\x81\xA7message\xA3bar",
+        expected: [{"message"=>"foo"}, {"message"=>"bar"}]
+      },
+      keep: true
+    )
+    data(
+      "String",
+      {
+        # "Hello msgpack".to_msgpack
+        input: "\xADHello msgpack",
+        expected: [nil]
+      },
+      keep: true
+    )
+    data(
+      "Array of String",
+      {
+        # ["foo", "bar"].to_msgpack
+        input: "\x92\xA3foo\xA3bar",
+        expected: [nil, nil]
+      },
+      keep: true
+    )
+    data(
+      "Array of String and Hash",
+      {
+        # ["foo", {message: "bar"}].to_msgpack
+        input: "\x92\xA3foo\x81\xA7message\xA3bar",
+        expected: [nil, {"message"=>"bar"}]
+      },
+      keep: true
+    )
+
+    def test_parse(data)
+      parsed_records = []
+      create_driver("").instance.parse(data[:input]) do |time, record|
+        parsed_records.append(record)
+      end
+      assert_equal(data[:expected], parsed_records)
+    end
+
+    def test_parse_io(data)
+      parsed_records = []
+      StringIO.open(data[:input]) do |io|
+        create_driver("").instance.parse_io(io) do |time, record|
+          parsed_records.append(record)
+        end
+      end
+      assert_equal(data[:expected], parsed_records)
+    end
+  end
+
+  # This becomes NoMethodError if a non-Hash object is passed to convert_values.
+  # https://github.com/fluent/fluentd/issues/4100
+  sub_test_case "execute_convert_values with null_empty_string" do
+    data(
+      "Normal hash",
+      {
+        # {message: "foo", empty: ""}.to_msgpack
+        input: "\x82\xA7message\xA3foo\xA5empty\xA0",
+        expected: [{"message" => "foo", "empty" => nil}]
+      },
+      keep: true
+    )
+    data(
+      "Array of multiple Hash",
+      {
+        # [{message: "foo", empty: ""}, {message: "bar", empty: ""}].to_msgpack
+        input: "\x92\x82\xA7message\xA3foo\xA5empty\xA0\x82\xA7message\xA3bar\xA5empty\xA0",
+        expected: [{"message"=>"foo", "empty" => nil}, {"message"=>"bar", "empty" => nil}]
+      },
+      keep: true
+    )
+    data(
+      "String",
+      {
+        # "Hello msgpack".to_msgpack
+        input: "\xADHello msgpack",
+        expected: [nil]
+      },
+      keep: true
+    )
+
+    def test_parse(data)
+      parsed_records = []
+      create_driver("null_empty_string").instance.parse(data[:input]) do |time, record|
+        parsed_records.append(record)
+      end
+      assert_equal(data[:expected], parsed_records)
+    end
+
+    def test_parse_io(data)
+      parsed_records = []
+      StringIO.open(data[:input]) do |io|
+        create_driver("null_empty_string").instance.parse_io(io) do |time, record|
+          parsed_records.append(record)
+        end
+      end
+      assert_equal(data[:expected], parsed_records)
+    end
+  end
+end
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