A clearing section includes a counter for measuring a period up to the reset of contents set by means of an operation panel to initial values. If a position discriminating section discriminates that the operation panel is at a first position, the clearing section starts measuring the period by means of the counter from the first entry made to the operation panel. When a count value reaches a predetermined value, the clearing section executes an automatic clear processing to reset the contents set by means of the operation panel to the initial values. On the other hand, the clearing section cancels the execution of the automatic clear processing if the position discriminating section discriminates that the operation panel is at a second position.