A terminal apparatus in a wireless communication system including a relay device that converts a signal of a first frequency to a second frequency, amplify the resulting signal, and relay the amplified signal to the base station apparatus, and be capable of using a plurality of frequencies as the second frequency, is provided. The terminal apparatus sends a search signal for searching for the relay device on at least one of the first frequency and the second frequency, detects, if the search signal is sent on the first frequency, the search signal on the second frequency, and if the search signal is sent on the second frequency, detect the search signal on the first frequency, determines that the relay device is present if the search signal having a converted frequency is detected.