Even when transmitted waves of multiple systems become approximately out of phase while diversity transmission is performed in a W-CDMA wireless system, synchronization establishment determination is more adequately performed. In a W-CDMA wireless system 1, even if it is determined in a normal synchronization establishment determination that synchronization cannot be established, when a phase difference in a common channel of a 0-system and a 1-system is within a certain range and a reception quality of the common channel (or a dedicated channel) has reached a certain level, it is determined that the synchronization can be established. Therefore, even when the transmitted waves of the multiple systems become approximately out of phase while the diversity transmission is performed in the W-CDMA wireless system, the synchronization establishment determination can be more adequately performed depending on whether or not communication is possible in an actual state.