Provided is an infrared light emitting device in which dark current and diffusion current caused by thermally excited holes are suppressed. Thermally excited carriers (holes) generated in a first n-type compound semiconductor layer (102) tend to diffuse in the direction of a π layer (105). But, the dark current by holes is reduced by providing an n-type wide band gap layer (103) with a larger band gap than the first layer (102) and the π layer (105) that suppresses the hole diffusion between the first layer (102) and the π layer (105). The wide band gap layer (103) has a band gap shifted relatively to valence band direction by n-type doping and thereby more effectively functions as a diffusion barrier for the thermally excited holes. Namely, the band gap and n-type doping of the wide band gap layer (103) are adjusted to suppress diffusion of the thermally excited carriers.