In a wireless communication system including a slave device, and a master device wirelessly connected to the slave device, the slave device includes a wireless communicator that performs wireless communication with the master device, a power supply unit that supplies power to each unit of the slave device, an interrupt detector that detects various interrupts, and a controller that controls the entire slave device, the interrupt detector supplies the power from the power supply unit to each unit of the slave device when detecting a timer interrupt occurring at predetermined intervals, and the controller performs control to perform an initialization process of the wireless communicator when the power is supplied from the power supply unit to each unit of the slave device, and perform an entire initialization process of the slave device when a capture signal is received via the wireless communicator.