diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9860c178..7df2903f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,7 @@
 
 ## develop (unreleased)
 ### New features
+* [#302](https://github.com/trema/pio/pull/302): Add new classes `Pio::Match::ConjunctionId`.
 * [#300](https://github.com/trema/pio/pull/300): Add new classes `Pio::Match::PacketReg{0..3}`.
 
 ## 0.30.0 (11/17/2015)
diff --git a/features/open_flow13/match.feature b/features/open_flow13/match.feature
index 6e895082..36912976 100644
--- a/features/open_flow13/match.feature
+++ b/features/open_flow13/match.feature
@@ -448,6 +448,16 @@ Feature: Match
       | tunnel_id      |                   1 |
       | tunnel_id_mask | 9223372036854775808 |
 
+  Scenario: new(conjunction_id: 1)
+    When I try to create an OpenFlow message with:
+      """
+      Pio::OpenFlow::Match.new(conjunction_id: 1)
+      """
+    Then it should finish successfully
+    And the message has the following fields and values:
+      | field          | value |
+      | conjunction_id |     1 |
+
   Scenario: new(packet_reg0: 1)
     When I try to create an OpenFlow message with:
       """
diff --git a/lib/pio/open_flow13/match.rb b/lib/pio/open_flow13/match.rb
index 9464354c..0084fcae 100644
--- a/lib/pio/open_flow13/match.rb
+++ b/lib/pio/open_flow13/match.rb
@@ -765,6 +765,19 @@ def length
         end
       end
 
+      # NXM_NX_CONJ_ID match field
+      class ConjunctionId < NiciraMatchExtensionValue
+        OXM_FIELD = 37
+
+        endian :big
+
+        uint32 :conjunction_id
+
+        def length
+          4
+        end
+      end
+
       # OXM_PACKET_REG0 match field
       class PacketReg0 < PacketRegistersValue
         OXM_FIELD = 0
@@ -906,6 +919,7 @@ class NiciraMatchExtension < BinData::Record
             masked_reg6 MaskedReg6
             reg7 Reg7
             masked_reg7 MaskedReg7
+            conjunction_id ConjunctionId
           end
 
           def length
@@ -944,6 +958,8 @@ def choose_tlv_value
               masked? ? MaskedReg6 : Reg6
             when Reg7::OXM_FIELD
               masked? ? MaskedReg7 : Reg7
+            when ConjunctionId::OXM_FIELD
+              ConjunctionId
             else
               fail "Unknown OXM field value: #{oxm_field}"
             end
@@ -1270,7 +1286,8 @@ def initialize(user_attrs)
            :ip_dscp, :ip_ecn, :tcp_source_port, :tcp_destination_port,
            :udp_source_port, :udp_destination_port,
            :sctp_source_port, :sctp_destination_port,
-           :icmpv4_type, :icmpv4_code, :arp_operation].each do |each|
+           :icmpv4_type, :icmpv4_code, :arp_operation,
+           :conjunction_id].each do |each|
             next unless user_attrs.key?(each)
             klass = Match.const_get(each.to_s.split('_').map(&:capitalize).join)
             @match_fields << { oxm_class: klass.superclass.const_get(:OXM_CLASS),