A vehicle seat comprises a seat bottom, a seat back pivotably attached to the seat bottom, a seat belt. The seat bottom has a support frame to be attached to a vehicle body, and a bottom cushion supported by the support frame. A pretensioner is disposed between the bottom cushion and the support frame to move the bottom cushion rearward with respect to the support frame when the unpreferable external force is generated. When the pretensioner is actuated, the bottom cushion moves rearward, and a moving distance S of a tip anchor and a tongue anchor is set larger than a moving distance T of the bottom cushion.