To provide a child safety seat capable of preventing the movement to the front of the head of a child when an accident occurs.

A child safety seat including a seat main body 10 and a base part 14 is fixed on the seat of a vehicle by the knee band of a vehicle seat belt. For movement between a first position and a second position, a front foot 28 is attached to the front part of the seat main body 10 so as to be pivotally moved and, in the second position, the front foot 28 is protruded downward from the seat main body 10 more than in the first position to compress the front part of the seat cushion 22 of the vehicle. Thus, the seat cushion 22 held between the front foot 28 and the rigid structure of the vehicle seat is compressed as much as possible to a maximum limit, the degree of movement in the angular direction of the child seat possible before, for example the front foot 28 is allowed to abut to the rigid structure of the vehicle seat in the middle of accident after attaching.