A working machine includes an operator's seat, a seat base supporting the operator's seat, and a slide rail for adjustment of a position of the operator's seat, the slide rail being located between the seat base and the operator's seat, in which the seat base includes a rail mount for attachment of the slide rail, the rail mount having a downward convex curve which is curved to deviate from the slide rail with increasing distance from each of opposite ends of the rail mount in a longitudinal direction of the slide rail and with decreasing distance to a center of the rail mount in the longitudinal direction.