A two-dimensional photonic crystal surface emitting laser comprising a laminated structure including: an active layer for generating light having a wavelength λ L by receiving an injection of an electric current; and a two-dimensional photonic crystal layer in which refractive index distribution is formed by modified refractive index regions two-dimensionally arranged in a plate-shaped base member, where a refractive index of the modified refractive index regions differs from that of the base member, the two-dimensional photonic crystal surface emitting laser emitting a laser beam in a direction of an inclination angle θ from a normal to the two-dimensional photonic crystal layer, characterized in that: the modified refractive index regions in the two-dimensional photonic crystal layer are modulated according to a modulation based on a modulation phase Ψ at respective lattice points of a basic two-dimensional lattice whose periodicity is determined such that a resonant state of the light having the wavelength λ L is created by forming a two-dimensional standing wave while the light having the wavelength λ L is prevented from being emitted to an outside, wherein a modulation means that a periodical change is given in a spatial period (modulation period) different from the spatial period of the basic two-dimensional lattice, to the state where the modified refractive index regions in the same form are respectively arranged at the exact lattice points of the basic two-dimensional lattice, and the modulation phase Ψ at each lattice point is expressed as Ψ=r↑·G'↑ by using a position vector r↑ of each lattice point and a reciprocal lattice vector G'↑=(g' x, g' y)=(k x ±|k↑|(sinθ cosφ)/n eff, k y ±|k↑|(sinθ sinφ)/n eff), the reciprocal lattice vector G'↑ being expressed by using: a wave vector k↑=(k x, k y) of the light having the wavelength λ L in the two-dimensional photonic crystal layer; an effective refractive index n eff of the two-dimensional photonic crystal layer; and an azimuthal angle φ from a predetermined reference line of the basic two-dimensional lattice. an active layer for generating light having a wavelength λ L by receiving an injection of an electric current; and a two-dimensional photonic crystal layer in which refractive index distribution is formed by modified refractive index regions two-dimensionally arranged in a plate-shaped base member, where a refractive index of the modified refractive index regions differs from that of the base member, the two-dimensional photonic crystal surface emitting laser emitting a laser beam in a direction of an inclination angle θ from a normal to the two-dimensional photonic crystal layer, characterized in that: the modified refractive index regions in the two-dimensional photonic crystal layer are modulated according to a modulation based on a modulation phase Ψ at respective lattice points of a basic two-dimensional lattice whose periodicity is determined such that a resonant state of the light having the wavelength λ L is created by forming a two-dimensional standing wave while the light having the wavelength λ L is prevented from being emitted to an outside, wherein a modulation means that a periodical change is given in a spatial period (modulation period) different from the spatial period of the basic two-dimensional lattice, to the state where the modified refractive index regions in the same form are respectively arranged at the exact lattice points of the basic two-dimensional lattice, and the modulation phase Ψ at each lattice point is expressed as Ψ=r↑·G'↑ by using a position vector r↑ of each lattice point and a reciprocal lattice vector G'↑=(g' x, g' y)=(k x ±|k↑|(sinθ cosφ)/n eff, k y ±|k↑|(sinθ sinφ)/n eff), the reciprocal lattice vector G'↑ being expressed by using: a wave vector k↑=(k x, k y) of the light having the wavelength λ L in the two-dimensional photonic crystal layer; an effective refractive index n eff of the two-dimensional photonic crystal layer; and an azimuthal angle φ from a predetermined reference line of the basic two-dimensional lattice. the modified refractive index regions in the two-dimensional photonic crystal layer are modulated according to a modulation based on a modulation phase Ψ at respective lattice points of a basic two-dimensional lattice whose periodicity is determined such that a resonant state of the light having the wavelength λ L is created by forming a two-dimensional standing wave while the light having the wavelength λ L is prevented from being emitted to an outside, wherein a modulation means that a periodical change is given in a spatial period (modulation period) different from the spatial period of the basic two-dimensional lattice, to the state where the modified refractive index regions in the same form are respectively arranged at the exact lattice points of the basic two-dimensional lattice, and the modulation phase Ψ at each lattice point is expressed as Ψ=r↑·G'↑ by using a position vector r↑ of each lattice point and a reciprocal lattice vector G'↑=(g' x, g' y)=(k x ±|k↑|(sinθ cosφ)/n eff, k y ±|k↑|(sinθ sinφ)/n eff), the reciprocal lattice vector G'↑ being expressed by using: a wave vector k↑=(k x, k y) of the light having the wavelength λ L in the two-dimensional photonic crystal layer; an effective refractive index n eff of the two-dimensional photonic crystal layer; and an azimuthal angle φ from a predetermined reference line of the basic two-dimensional lattice.