In a swallowable capsule endoscope, an imaging timing generating circuit (26) generates a highly accurate imaging reference clock to set an imaging timing of a CCD (23) an RF clock frequency dividing circuit 26a divides a frequency of the imaging reference clock, and supplies a resulting clock as an RF clock to an RF transmitting unit (27) and a PLL circuit (27a) in the RF transmitting unit (27) synchronizes a phase of an RF reference clock with a phase of the RF clock. Thus, the RF reference clock can be stably oscillated, and fluctuation in a transmission frequency of a transmission carrier wave can be suppressed.
