The present invention provides a semiconductor light emitting element that can obtain oscillation at desired wavelengths. The semiconductor light emitting element comprises a semiconductor substrate 11, an active layer 12 for emitting and propagating light, which is formed in a stripe shape above the semiconductor substrate 11, buried layers 13a, 13b formed on both lateral sides of the active layer 12, a cladding layer 16 formed above the active layer 12 and the buried layers 13a, 13b, a first electrode 17a formed above the cladding layer 16, and a second electrode 17b formed below the semiconductor substrate 11. The active layer 12 opens on one end facet 14a among the two end facets formed by cleavage so that the active layer 12 makes a predetermined angle to the normal direction of the one end facet 14a. A partially heating means 15 for heating a predetermined length portion of the active layer 12 along the direction of light propagation is formed on a first electrode at a position thermally isolated from the one end facet 14a.