Abstract: A rotary cultivating apparatus wherein a tiller frame having a rotary tiller unit is laterally shiftable relative to a fixed frame having connecting portions for a vehicle and a power input shaft. A mechanism for laterally shifting the tiller frame comprises a transmission gear member mounted on a transmission shaft for the tiller unit and having an inner gear and an outer gear, a shifting screw rod reversibly rotatable by the transmission gear member through intermediate gears, and an internally threaded member fixed to tiller frame and in screw-thread engagement with the screw rod. One of the intermediate gears is selectively meshable with the transmission gear member to shift the tiller frame laterally in either direction by utilizing the power for driving the tine shaft of the tiller unit.