A method for manufacturing a semiconductor device, by which a multiple quantum well structure having a large number of pairs can be efficiently grown while maintaining good crystalline quality, and the semiconductor device, are provided. The semiconductor device manufacturing method of the present invention includes a step of forming a multiple quantum well structure 3 having 50 or more pairs of group III-V compound semiconductor quantum wells. In the step of forming the multiple quantum well structure 3, the multiple quantum well structure is formed by metal-organic vapor phase epitaxy using only metal-organic sources (all metal-organic source MOVPE).