diff --git a/app/models/registration.rb b/app/models/registration.rb
index 2f2d5c68..6b35e759 100644
--- a/app/models/registration.rb
+++ b/app/models/registration.rb
@@ -29,6 +29,7 @@ class Registration < ActiveRecord::Base
   validate :registration_limit_not_exceed, on: :create
 
   after_create :set_week, :subscribe_to_conference, :send_registration_mail
+  after_destroy :destroy_purchased_tickets
 
   def week
     created_at.strftime('%W').to_i
@@ -36,6 +37,13 @@ class Registration < ActiveRecord::Base
 
   private
 
+  def destroy_purchased_tickets
+    ticket_purchased = TicketPurchase.where(conference_id: conference_id)
+    unless ticket_purchased.empty?
+      ticket_purchased.destroy_all
+    end
+  end
+
   def subscribe_to_conference
     Subscription.create(conference_id: conference.id, user_id: user.id)
   end