Provided is a transmission and reception signal detecting apparatus, which includes a directional coupler and a signal detecting part. The directional coupler includes a first port and a second port. The signal detecting part is connected to the first and second ports of the directional coupler and detects an output of a first signal transmitted through the first port and an output of a second signal transmitted through the second port. The signal detecting part is connected to the first port under a first operation condition. The signal detecting part is connected to the second port under a second operation condition.