According to one embodiment, a method is disclosed for manufacturing a nitride semiconductor layer. The method can include forming a first nitride semiconductor layer on a substrate in a reactor supplied with a first carrier gas and a first source gas. The first nitride semiconductor layer includes indium. The first carrier gas includes hydrogen supplied into the reactor at a first flow rate and includes nitrogen supplied into the reactor at a second flow rate. The first source gas includes indium and nitrogen and supplied into the reactor at a third flow rate. The first flow rate is not less than 0.07% and not more than 0.15% of a sum of the first flow rate, the second flow rate, and the third flow rate.