There are provided a base station device and a mobile station device for increasing the speed of cell search by introducing identification of TTI timing into the cell search. In the base station device (100), a frame configuration unit (120) forms a frame by arranging a TTI synchronization sequence (SCH1 sequence) used for identifying the frame timing and a TTI synchronization sequence (SCH2 sequence) used for identifying the TTI timing in such a manner that they are not superimposed on the same symbol specified by the frequency and the time. A radio transmission unit (145) sends the frame. The frame configuration unit (120) arranges the frame synchronization sequence at a predetermined position from the frame starting symbol and the TTI synchronization sequence at a predetermined position from the TTI starting symbol. The mobile station device (200) receiving the frame detects the TTI timing by using the TTI synchronization sequence.