Provided are a semiconductor laser manufacturing method and a semiconductor laser with a low device resistance. First, an active layer is deposited above a GaN substrate of a first conductivity type. A first guide layer made of GaN of a second conductivity type is deposited above the active layer. An AlN layer is deposited on the first guide layer. An opening is formed in the AlN layer. A first cladding layer made of a group-III nitride semiconductor of the second conductivity type is formed on the AlN layer and the first guide layer exposed through the opening such that a first growth rate at a start of growth on the first guide layer exposed through the opening becomes greater than a second growth rate at a start of growth on the AlN layer. A contact layer of the second conductivity type is formed on the first cladding layer.