In a transmitter which transmits a signal by a DSTBC scheme, communication is efficiently performed by the DSTBC scheme. In the transmitter which transmits the signal by the DSTBC scheme, a frame in which a sync word is disposed in a predetermined position subsequent to the head is used. Initial value controller (31 to 35) sets initial values of differential encoding (differential encoding unit 15) when a DSTBC encoder which processes a transmission target processes the frame on the basis of values from the head of the frame to a position before the sync word so that a signal point corresponding to the position immediately before the sync word in the DSTBC encoder which processes the transmission target becomes a specific point.