A semiconductor light emitting device comprises: a substrate having first and second major surfaces; a light emitting layer provided in a first portion on the first major surface of the substrate; a first electrode provided above the light emitting layer; a second electrode provided in a second portion on the first major surface of the substrate, the second portion being different from the first portion; and a protrusion provided on the second major surface of the substrate, the protrusion having a planar shape that reflects a planar shape of a light emitting area of the light emitting layer, the light emitting area being sandwiched between the first electrode and the second electrode and facing the protrusion.