A terminal device, a base station device, a communication system, a measurement method, and an integrated circuit, which are capable of efficiently performing Sidelink Direct Discovery, are provided. In the terminal device, a reception unit is configured to receive an RRC connection reconfiguration message including a first configuration related to Sidelink Direct Discovery, and in a case where the first configuration includes frequency information, to attempt to acquire configuration information about monitoring of a Sidelink Direct Discovery announcement at a frequency indicated by the frequency information, using a timer configured to count a predetermined time and while the timer is counting, by acquiring system information to be broadcast at the frequency.