diff --git a/app/services/tables/swap.rb b/app/services/tables/swap.rb
index f7d3d26..4bf79bd 100644
--- a/app/services/tables/swap.rb
+++ b/app/services/tables/swap.rb
@@ -8,6 +8,8 @@ module Tables
     def each
       @initial_solution.tables.combination(2) do |table_a, table_b|
         table_a.swap_candidates.product(table_b.swap_candidates).each do |(person_a, person_b)|
+          next if person_a.affinity_group_list.first == person_b.affinity_group_list.first
+
           new_solution = @initial_solution.dup
 
           new_table_a = table_a.dup