To provide a growing method for forming a buffer layer excellent in planarity and degree of orientation and having excellent buffer function on a ZnO single crystal substrate, and also forming a ZnO single crystal excellent in planarity and degree of orientation, and having high complete performance of low defect and transition density and in a high thermally stable state on the buffer layer, and also to provide a semiconductor element having high performance and high reliability, specifically a semiconductor light emitting element excellent in light emitting efficiency and an element service life.

The method for growing a zinc oxide-based semiconductor has: a low temperature growing step for growing a buffer layer of a ZnO-based single crystal by using an organic metal compound not containing oxygen and a polar oxide material on a substrate at a growing temperature in a range of 250-450°C by an MOCVD method; a step for executing heat treatment for the buffer layer to transit the buffer layer to a single crystal layer in a thermally stable state; and a high temperature growing step for growing a ZnO-based single crystal by using an organic metal compound not containing oxygen and a polar oxygen material on the single crystal layer in a thermally stable state at a growing temperature of a range of 600-900°C.