A mobile station device which can correctly search for another cell quickly in a communication system using the OFCDM method. A blank subcarrier correlation calculating section (502) calculates the correlation between the blank subcarriers of the CPICH symbols adjacent to the cell signal of this mobile station device. A correlation-between-adjacent-symbols calculating section (503) calculates correlation between adjacent symbols in the frequency direction. A correlation value comparing section (505) compares the correlation values inputted from the correlation-between-adjacent-symbols calculating section (503) and detects the boundary between adjacent symbols having the maximum correlation value as a frame timing of the another cell. If the correlation value of the blank subcarrier correlation calculating section (502) is below a predetermined threshold, the correlation value comparing section (505) detects the frame timing having the maximum correlation value other than the frame timing of this cell as the frame timing of the another cell. If the correlation value is the threshold value or more, the correlation value comparing section (505) detects the frame timing of this cell as the frame timing of the another cell.