The method for manufacturing a linear motion guide device includes a step of forming a long member (8) having a pair of side wall parts (51) and a bottom wall part (52), a step of attaching a track body (4) to the pair of side wall parts (51) of the long member (8), and a step of cutting away a base member (5) to which the track body (4) is attached by cutting the long member (8) together with the track body (4) into a desired length.