A child safety seat includes a seat shell having two sidewalls respectively provided at a left and a right side of the seat shell for restricting sideways movement of a child, a buffering part connected with the seat shell, a retaining mechanism and a release mechanism. The buffering part is movable between a first position retracted toward one of the two sidewalls, and a second position protruding sideways from the sidewall. The retaining mechanism is operable to hold the buffering part in the first position. The release mechanism includes an operating device that is disposed in a region of the seat shell between the two sidewalls and is operatively connected with the retaining mechanism, the operating device being operable to release the buffering part from the hold of the retaining mechanism for movement of the buffering part from the first position to the second position.