A method of fabricating a semiconductor device includes the steps of forming a step region having a mesa shape in a direction of <011> or <0-11> on a (100) plane of an InP-based compound semiconductor crystal, and burying the step region with InP-based buried layers grown by vapor-phase growth by supplying a base gas to which a chlorinated organic compound is added, the organic chlorine compound including at least two carbon atoms, and each of the carbon atoms is bonded to one chlorine (Cl) atom in one molecule. The chlorinated organic compound is any one of 1,2-dichloroethane, 1,2-dichloropropane, and 1,2-dichloroethylene.