A base station apparatus includes: decoding units for an uplink control signal and an uplink shared data signal; and a reliability determination unit configured to determine a degree of reliability that predetermined information is included in the uplink control signal that is received periodically. In the case where timing of a predetermined period for the predetermined information agrees with reception timing of the uplink shared data signal, (1) whether to perform decoding by assuming that the uplink shared data signal includes the predetermined information is determined according to whether the period is equal to or less than a radio frame length, (2) if the period is longer than the radio frame length, whether to decode the uplink shared data signal by assuming that the uplink shared data signal includes the predetermined information is determined according to whether the degree of reliability is higher than a predetermined value.