A strain wave gear apparatus includes a rigid internal gear, a flexible external gear, and a wave generator. The wave generator includes an input shaft fixing member including eccentric cams, bearings respectively fixed to outer sides of the eccentric cams, and housings respectively fitted to outer peripheral surfaces of the bearings. The eccentric cams are arranged side by side in a direction of an inclined axis inclined with respect to an input rotation axis at an inclination angle (θ) in a manner that respective center axes of the eccentric cams are parallel to the inclined axis and decentered in directions opposite to each other from the inclined axis. The housings are each formed into a tapered shape so that an outer peripheral surface of each of the housings is held in surface contact with an inner peripheral surface of the flexible external gear.