A semiconductor light emitting device includes a first cladding layer, a second cladding layer, and an active layer formed between the first and second cladding layers. A diffusion control layer includes an intermediate layer and a first transparent conductive layer provided on the second cladding layer in this order. The semiconductor light emitting device further includes a second transparent conductive layer having an impurity in a concentration lower than an impurity concentration of the diffusion control layer, and a third transparent conductive layer having an impurity in a concentration higher than the impurity concentration of the second transparent conductive layer. The boundary between the intermediate layer and the first transparent conductive layer is a lattice mismatch interface.