A baby carrier with an adjustable back plate comprises a main body, a back plate, a belt and a belt adjustment mechanism. The main body has a bottom wall, two long side walls and two short side walls. The back plate is pivoted on the bottom wall for support baby-occupant in a selected inclination. The belt has a distal end affixed to one side of the main body and an adjustable length for passing across underneath the back plate for retaining the back plate in the selected inclination angle. The belt adjustment mechanism is mounted on the opposite side of the main body for adjusting the adjustable length of the belt by pulling the free end thereof and pressing the back plate downwardly just under the instinct of the care-giver.