To provide a release mechanism by which release operation can be performed with good responsiveness with its simple composition and also working environment can be improved by its low noise.

When a release signal is sent to a servomotor 410 by linking with pressing work by a pressing part 300, the servomotor 410 is rotated and the output member 421 of a ball screw part 420 is moved into a release direction. An arm member 431 is rotated by a prescribed amount with the movement of the output member to the release direction and an eccentric cam 434 is rotated by a prescribed amount. A hydraulic cylinder 440 is lifted in the release direction by the amount of lift corresponding to an angular position because the eccentric cam 434 is arranged eccentrically to the center of rotation of a shaft 433. An upper frame 241 is pivotally moved in the release direction around a pivot 245 and a workpiece 2 is released because the output member 441 of the hydraulic cylinder 440 is connected to the upper frame 241 in a connecting part 442.