A call reception infeasibleness informing system and method for informing, if a called-side portable telephone terminal (10), which is a called-side telephone terminal, cannot receive any call in some reason, the calling-side portable telephone terminal (20), which is a calling-side portable telephone, of the reason for the infeasibleness and the time zone during which the portable telephone terminal cannot receive any call. The reason for infeasibleness of call reception and the time zone during which any call cannot be received are entered into a called-side portable telephone terminal (10) and stored in the called-side portable telephone terminal (10), which is a storage means, or a computer (6). When the time at which the calling-side portable telephone terminal (20) call the called-side portable telephone terminal (10) is within the time zone, the called-side portable telephone terminal (10), which is a notifying means, or the computer (6) executes a processing for notifying the calling-side portable telephone terminal (20) of the reason and time zone. The caller is notified of the reason and time zone in the form of automatic speech and/or text information by the calling-side portable telephone terminal (20).