An optical waveguide device has: photonic crystal regions 305, each having holes 304 arranged in a periodic array; and an optical waveguide 302. Within the waveguide 302, high refractive index portions 303 are arranged along the waveguiding direction. Each of the high refractive index portions 303 is generally interposed between a pair of holes 304 which are in symmetric positions with respect to the center axis. The center of gravity of every high refractive index portion 303 is shifted along the waveguiding direction from a midpoint of a line interconnecting centers of the pair of holes 304, and is located between a position which is 0.45 r away from the midpoint in the waveguiding direction and a position which is 0.25 r away from the midpoint in the opposite direction, where r is a radius of each hole 304.