A head is moved in a lateral direction on the boundary between a separation track and a recording track on a recording medium. The separation track isolates the adjacent recording tracks from each other. A variation is detected in the output supplied from the head based on the recording track. Positional information indicating the position of the head is generated based on the variation. The output supplied from the head varies in response to the movement in the lateral direction, namely the elapsed time. The positional information can thus be generated based on the variation in the output. The generated positional information contributes to an accurate positioning in a facilitated manner. Moreover, information required to position the head can be omitted from the recording medium. The processes can be simplified in the production of the recording medium. The operation time can thus be shortened.