To simultaneously transmit data related to two channels using code division data related to a first channel (DTCH) are spread parallely using a first spreading code (C.sub.I) and a second spreading code (C.sub.Q), data related to a second channel (PCCH) are spread parallely using a first spreading code (C.sub.I) and a second spreading code (C.sub.Q), the power level of a signal representing said data related to the second channel (PCCH) after the spreading is changed (G) with respect to the power level of a signal representing the data related to the first channel (DTCH) after the spreading, and a transmission is compiled from spread data related to the first channel and spread data related to the second channel the power level of which has been changed.