A maintenance tool for a planetary gear comprises a force generating device (101) comprising an actuator (102) for fastening to an end of a planet wheel pin of the planetary gear and for directing axial force to the planet wheel pin, and a body structure (104) for mechanically supporting a frame of the force generating device with respect to the planet carrier of the planetary gear so as to allow the actuator to move the planet wheel pin axially with respect to the planet carrier. In many cases, the maintenance tool enables removal of a planet wheel pin and installing, the same or another planet wheel pin at an operating site of the planetary gear. Thus, there is no need to move the planetary gear away from its operating site, e.g. a nacelle of a wind power plant, for maintenance work comprising removal of one or more planet wheel pins.