PURPOSE: To prevent the occurrence of the multiple reception of a charge for use due to the duplicate operation of a start key.

CONSTITUTION: The control part 10 of a card controller 1 invalidates next operation input during the output of a start signal and during prescribed period corresponding to time, at least, to the output of a busy signal after the end of the output of the start signal in addition to the case that the busy signal is being outputted from the operation control part 20 of a washing machine 2 even if the next operation input by the start key 13 is inputted after the start key 13 is operated first, and after the first operation by the start key 13 is given, it invalidates the next operation of the start key 13 until the operation of the washing machine is finished.