An active area includes a photonic-crystal optical waveguide formed by periodically arranging a plurality of holes in a primary plane direction of an active-area core layer in an active-area growth portion. A passive area includes a passive optical waveguide formed in a passive-area growth portion. An effective refractive index of a growth structure of the active-area growth portion is larger than an effective refractive index of a growth structure of the passive-area growth portion, and an active layer has a gain at a zero group-velocity point positioned on a high-frequency side of a dispersion curve of the photonic-crystal optical waveguide.