A communication system that transmits individual control information to a plurality of respective user terminals using a shared control channel, wherein when transmitting individual control information and prescribed control information to the user terminals, a base station device divides user terminals into groups according to the contents of the prescribed control information for the respective user terminals, arranges the individual control information for each user terminal in a specified group order, creates number-in-group information wherein the number of user terminals belonging to each group is arranged in the group order, and transmits the number-in-group information together with the individual control information for each user terminal in the group order.