To make it possible to smoothly operate a lock device by using electromagnetic wave signals even under a poor environment for receiving electromagnetic wave.

Normally, electromagnetic wave containing a first code signal 11 and a second code signal 12 is received, and a control signal to a lock device 5 is generated when both of the first code signal 11 and the second code signal 12 are confirmed to be predetermined code signals. In a poor receiving state, if both the first code signal 11 and the second code signal 12 are not confirmed to be predetermined signals or either the first code signal 11 or second code signal 12 are confirmed to be the predetermined code signal, then the switching counter is advanced. When the switching counter counts a value higher than the predetermined value and either the first code signal 11 or the second code signal 12 verifies the predetermined code signal, then a control signal to the lock device 5 will be generated.