A shock absorber includes a cylinder including a working chamber therein; a rod configured to be axially movably inserted into the cylinder; and a plurality of tanks configured to be integrally attached to the cylinder, wherein an interior of one of the tanks is comparted into a liquid chamber configured to be communicated with the working chamber and filled with liquid and an air chamber filled with gas, and a sub-air chamber configured to be communicated with the air chamber is formed in the other tank.