A child safety seat includes a seat shell and a buffering part. The seat shell includes a backrest portion and two sidewalls, the backrest portion having a front surface facing forward that is suitable to provide support for a child's back, the two sidewalls being respectively disposed at a left and a right side of the seat shell for restricting sideways movements of a child who sits in the seat shell, one of the two sidewalls having a sidewall portion located in front of the front surface. The buffering part is connected with the seat shell, the buffering part being operable to protrude sideways at an outer side of the sidewall portion.