Provided are a semiconductor layer manufacturing method and a semiconductor manufacturing apparatus capable of forming a high quality semiconductor layer even by a single chamber system, with a shortened process time required for reducing a concentration of impurities that exist in a reaction chamber before forming the semiconductor layer. A semiconductor device manufactured using such a method and apparatus is also provided. The present invention relates to a semiconductor layer manufacturing method of forming a semiconductor layer inside a reaction chamber (101) capable of being hermetically sealed, including an impurities removing step of removing impurities inside the reaction chamber (101) using a replacement gas, and a semiconductor layer forming step of forming the semiconductor layer, the impurities removing step being a step in which a cycle composed of a replacement gas introducing step of introducing the replacement gas into the reaction chamber (101) and an exhausting step of exhausting the replacement gas is repeated a plurality of times, the impurities removing step being performed at least before the semiconductor layer forming step.