In a semiconductor light emitting device, a semiconductor light emitting element has a light extracted surface on which a plurality of convex structures is formed. The convex structures each have a conical mesa portion constituting a refractive index gradient structure, a cylindrical portion constituting a diffraction grating structure, and a conical portion constituting a refractive index gradient structure. The mesa portion, cylindrical portion, and conical portion are arranged in this order from the light extracted surface. The period between the convex structures is longer than 1/(the refractive index of an external medium+the refractive index of the convex structures) of an emission wavelength and equal to or shorter than the emission wavelength. The circle-equivalent average diameter of the cylindrical portion is 1/3 to 9/10 of that of the bottom of the mesa portion.