An optical wavelength multiplexing/de-multiplexing circuit which is configured with an arrayed waveguide grating and a Mach-Zehnder interferometer circuit, said arrayed waveguide grating comprising: an arrayed waveguide including a waveguide having a length sequentially increased by a certain optical path length difference; first and second slab waveguides (301, 302) connected to both end parts of said arrayed waveguide, respectively; and temperature compensation means for compensating a main temperature dependence at a transmission wavelength, and said Mach-Zehnder interferometer circuit comprising: first and second arm waveguides (308, 309) having a certain optical path length difference therebetween; a latter stage optical coupler connected between one end in each of said first and second arm waveguides (308, 309) and an end part of said fist slab waveguide; a former stage optical coupler connected to the other end in each of said first and second arm waveguides (308, 309); and temperature compensation means for compensating a main temperature dependence at a transmission wavelength, characterized in that said former stage optical coupler is a phase difference generation coupler configured with: a first optical coupler causing light to branch in a specific intensity ratio; a third arm waveguide and a fourth arm waveguide further connected to said first optical coupler and having a certain optical path length difference therebetween; and a second coupler further connected to each of said third and fourth arm waveguides (313, 314), and further connected to each of said first and second arm waveguides (308, 309) in said Mach-Zehnder interferometer circuit; the former stage optical coupler including a mechanism which changes the optical path length difference between said third arm waveguide and said fourth arm waveguide by temperature and is configured so as to cause a temperature dependence of the transmission wavelength in said Mach-Zehnder interferometer circuit, the temperature dependence being modulated by a temperature-induced change of a phase difference between two outputs of said phase difference generation coupler, to compensate a remaining temperature dependence of the transmission wavelength in said arrayed waveguide grating; said mechanism is a groove which is formed so as to divide only said third arm waveguide and in which material having a refractive index temperature coefficient different from a temperature coefficient of an effective refractive index of said third and fourth arm waveguides (313, 314) is inserted; and a light intensity branching ratio to said third arm waveguide is smaller than 50% in said first optical coupler. an arrayed waveguide including a waveguide having a length sequentially increased by a certain optical path length difference; first and second slab waveguides (301, 302) connected to both end parts of said arrayed waveguide, respectively; and temperature compensation means for compensating a main temperature dependence at a transmission wavelength, and first and second arm waveguides (308, 309) having a certain optical path length difference therebetween; a latter stage optical coupler connected between one end in each of said first and second arm waveguides (308, 309) and an end part of said fist slab waveguide; a former stage optical coupler connected to the other end in each of said first and second arm waveguides (308, 309); and temperature compensation means for compensating a main temperature dependence at a transmission wavelength, a first optical coupler causing light to branch in a specific intensity ratio; a third arm waveguide and a fourth arm waveguide further connected to said first optical coupler and having a certain optical path length difference therebetween; and a second coupler further connected to each of said third and fourth arm waveguides (313, 314), and further connected to each of said first and second arm waveguides (308, 309) in said Mach-Zehnder interferometer circuit; the former stage optical coupler including a mechanism which changes the optical path length difference between said third arm waveguide and said fourth arm waveguide by temperature and is configured so as to cause a temperature dependence of the transmission wavelength in said Mach-Zehnder interferometer circuit, the temperature dependence being modulated by a temperature-induced change of a phase difference between two outputs of said phase difference generation coupler, to compensate a remaining temperature dependence of the transmission wavelength in said arrayed waveguide grating; said mechanism is a groove which is formed so as to divide only said third arm waveguide and in which material having a refractive index temperature coefficient different from a temperature coefficient of an effective refractive index of said third and fourth arm waveguides (313, 314) is inserted; and a light intensity branching ratio to said third arm waveguide is smaller than 50% in said first optical coupler.