A mobile object according to the present invention includes: a moving base 1, 201, 301 which includes a front base 13, 213, 313 having front wheel 11 and a rear base 14, 214, 314 having rear wheel 12; and a seat 2, 302 which includes a seating part 21 having a seating surface 21a and leg part 22, 322 supporting the seating part 21. The front base 13, 213, 313 and the rear base 14, 214, 314 are movable relative to each other to expand and contract a wheel base H. The seating part 21 is movable backward and forward respectively by movement of the leg part 22, 322 in association with relative movement of the front base 13, 213, 313 and the rear base 14, 214, 314 for expansion and contraction of the wheel base H. Thus, the mobile object can be efficiently used in a folded state, and user-friendliness of the mobile object can be enhanced.