A fall arrest device used with a fixed safety rope comprises a support arm articulated on a first spindle of the body, a roller in the form of a cylindrical wheel mounted rotating free on a second spindle securedly attached to the support arm, and a centrifugal coupling arranged between a drive member of the roller and the support arm so as to occupy a disengaged position or an engaged position. The centrifugal coupling comprises at least one flyweight movable along a ramp of the drive member against a compression spring, and a connecting interface engaged inside a cylindrical rim of the support arm to transmit the elastic force of the spring to the flyweight.