To compose a shock absorber capable of obtaining different damping forces in the elongation direction and the compression direction and capable of widely adjusting the damping forces.

A main communication oil passage P and an auxiliary communication oil passage Q are formed between a first oil passage L1 communicating with a first oil chamber S1 on a bottom side and a second oil passage L2 communicating with a second oil chamber S2 on a piston rod side. The main communication oil passage P is provided with a first variable orifice OR1, a second variable orifice OR2, and an electric motor M for adjusting opening degrees of these orifices. The auxiliary communication oil passage Q is equipped with a first check valve CH1 and a second check valve CH2, and an accumulator A is provided between the main communication oil passage P and the auxiliary communication oil passage Q.