A quick-release mechanism of an actuator, including: a worm wheel having a circular body section, a shaft hole extending through the body section along a curvature center line thereof; a rod-like push body coaxially fitted through the shaft hole; and a clutch unit having a first clutch section and a second clutch section. The first clutch section is integrally formed on an end face of the body section. The second clutch section is slidably and relatively unrotatably fitted on the push body. The second clutch section is movable along an axis of the push body between a disengaging position and an engaging position. When positioned in the engaging position, the first and second clutch sections are engaged to drivingly couple the push body with the worm wheel. When positioned in the disengaging position, the first and second clutch sections are disengaged to uncouple the push body from the worm wheel.