Height-adjustable armrest

A height-adjustable armrest for a chair, comprising:

• a body comprising an arm support section on an upper end thereof for supporting an arm of a user, the body further comprising a tubular section having a vertical slot with a plurality of vertically spaced positioning grooves, a reduced section being formed between a pair of the positioning grooves adjacent to each other;
• a coupling seat comprising a longitudinal hole and mounted around the tubular section of the body, the coupling seat comprising a coupling section that has a through-hole in communication with the longitudinal hole of the coupling seat;
• an adjusting device mounted to the coupling section, the adjusting device comprising a positioning member, an elastic element, and a push button, the positioning member extending through the through-hole of the coupling seat and the vertical slot of the body, the positioning member including a first end in the tubular section and a second end connected to the push button to move therewith, the first end of the positioning member including a positioning section that is releasably and selectively engaged in one of the positioning grooves, the elastic element being mounted between the coupling seat and the push button for biasing the positioning section of the positioning member into one of the positioning grooves, the positioning section having a width greater than that of each said reduced section of the body, the positioning section of the positioning member being disengaged from the positioning grooves when the push button is pushed, allowing adjustment of a height of the body;
• and
• a connecting frame including a first engaging portion securely connected to the coupling seat and a second engaging portion securely connected to a seat of a chair.