A rider-posture changing device is for a human-powered vehicle. The rider-posture changing device includes a first member, a second member, a positioning structure and an electric actuator. The second member is configured to be movable relative to the first member. The positioning structure is configured to adjustably position the first member relative to the second member. The electric actuator is configured to actuate the positioning structure. The electric actuator includes a first electrical connector and a second electrical connector. The first electrical connector is configured to be detachably and reattachably connected to a first power supply. The second electrical connector is configured to be detachably and reattachably connected to a second power supply.