A shock absorber includes a stationary part; a steering part extending in a longitudinal direction and rotatably coupled to the stationary part by a rotation axis in the longitudinal direction; a sliding part which forms an internal space containing fluid between the steering part and slidably coupled to the steering part in a direction in which the steering part extends; an elastic body having both ends respectively coupled to the steering part and the sliding part to support the steering part and the sliding part and maintain the internal space between the steering part and the sliding part; a flow path formed in the sliding part and configured to communicate the internal space between the steering part and the sliding part to outside so that the fluid can flow; and a steered driving wheel slidably connected to the sliding part.