Child safety seat

A child safety seat is provided with a backrest including two parallel recesses longitudinally disposed on a back; a headrest including a sliding plate slidably disposed in the recesses; a cover plate secured to the headrest; an adjustment handle slidably secured to the headrest and including opposite first and second wedges; a belt member having a bottom end secured to the backrest and a top end secured to the cover plate; first and second retaining members proximate a lower edge of the cover plate and fastened between the first and second wedges; a first adjustment member pivotably secured to the first retaining member and including first inclined teeth, and a first lever proximate the first wedge; a second adjustment member pivotably secured to the second retaining member and including second inclined teeth, and a second lever proximate the second wedge; a first torsion spring pivotably secured to the first retaining member; and a second torsion spring pivotably secured to the second retaining member. The belt member passes between the first teeth and a base of the first retaining member, and between the second teeth and a base of the second retaining member. A downward pushing of the adjustment handle lowers the headrest or an upward pulling of the adjustment handle lifts the headrest in one hand operation. It is very convenient.