Key control for a key matrix circuit having a plurality of keys is provided to reduce power consumption in key searching caused by unintended key pressing. In key control on the key matrix circuit having a plurality of rows and columns of keys (key switches) in matrix arrangement, keys are disabled or enabled in row lines or in column lines on the key matrix circuit by any one of the lines through key selection by a key selecting means (opening/closing detection circuit, opening/closing detecting unit, key selection switch, key selecting unit). Following key selection, a control means (control unit) keeps key pressing detection in a standby status for a predetermined time in response to an event of detection of a press of a key included in enabled keys, and resumes the key pressing detection after the passage of the predetermined time.