Disclosed is a backrest adjusting mechanism used in a
high chair for infants, toddlers and
small children and installed in the hollow section of the backrest body of the
high chair, which includes a fixed
handle, a movable
handle, a set of springs, a movable rod, and a horizontal lever for adjusting the inclination angle of the backrest portion of the
high chair, in which the springs are connected between the movable rod and the movable
handle. The backrest adjusting mechanism is characterized in that a first groove is formed in each of the two bottom sides of the movable rod of the backrest adjusting mechanism, and a second groove is formed in each of the two bottom sides of the backrest body, and said horizontal lever penetrates through the bottom of the backrest body and communicates to said first and second grooves. When the inclination angle of the backrest portion is intended to be adjusted, the movable handle is pulled to jointly drag the movable rod so that the horizontal lever can be released from the position where it is previously hold. At this point, the inclination angle of the backrest portion can be adjusted. When the desired inclination angle is reached, the backrest portion of the high chair can be easily fixed at this desired inclination position by simply releasing the movable handle. In this way, the backrest portion of the high chair can be adjusted at will.