An apparatus for frame transmission includes a dummy data inserting unit that inserts dummy data, at timing of an interval in which a received frame input intermittently is not detected, in a sequence of processing processes of scrambling processing of user data cut out from the received frame, reading-out of the data after the scrambling processing with a parity appended thereto from a memory and parity checking thereof, and descrambling processing of the data after the parity checking, and an error determining unit that determines whether an error is occurring in the sequence of the processing processes, based on the dummy data obtained by the descrambling processing of the dummy data inserted in the sequence of the processing processes by the dummy data inserting unit.