A multilayer film reflective mirror comprising: a first multilayer film formed by alternately laminating first substance layers of a first substance and second substance layers of a second substance on a substrate; and a second multilayer film formed by alternately laminating first substance layers of the first substance and second substance layers of the second substance on the first multilayer film, wherein: a difference between a refractive index of the first substance in the X-ray region and the refractive index of a vacuum is relatively large, and a difference between a refractive index of the second substance in the X-ray region and the refractive index of a vacuum is relatively small; and characterised in that: each thickness of the first substance layers in the first multilayer film is substantially equal to or smaller than each thickness of the first substance layers in the second multilayer film; and the ratio of the thickness of the layers of the first substance to the thickness of the layers of the second substance in the first multilayer film is different from the ratio of the thickness of the layers of the first substance to the thickness of the layers of the second substance in the second multilayer film, so as to reduce the internal stress of the multilayer film reflective mirror. a first multilayer film formed by alternately laminating first substance layers of a first substance and second substance layers of a second substance on a substrate; and a second multilayer film formed by alternately laminating first substance layers of the first substance and second substance layers of the second substance on the first multilayer film, wherein: a difference between a refractive index of the first substance in the X-ray region and the refractive index of a vacuum is relatively large, and a difference between a refractive index of the second substance in the X-ray region and the refractive index of a vacuum is relatively small; and characterised in that: each thickness of the first substance layers in the first multilayer film is substantially equal to or smaller than each thickness of the first substance layers in the second multilayer film; and the ratio of the thickness of the layers of the first substance to the thickness of the layers of the second substance in the first multilayer film is different from the ratio of the thickness of the layers of the first substance to the thickness of the layers of the second substance in the second multilayer film, so as to reduce the internal stress of the multilayer film reflective mirror. a difference between a refractive index of the first substance in the X-ray region and the refractive index of a vacuum is relatively large, and a difference between a refractive index of the second substance in the X-ray region and the refractive index of a vacuum is relatively small; and characterised in that: each thickness of the first substance layers in the first multilayer film is substantially equal to or smaller than each thickness of the first substance layers in the second multilayer film; and the ratio of the thickness of the layers of the first substance to the thickness of the layers of the second substance in the first multilayer film is different from the ratio of the thickness of the layers of the first substance to the thickness of the layers of the second substance in the second multilayer film, so as to reduce the internal stress of the multilayer film reflective mirror. each thickness of the first substance layers in the first multilayer film is substantially equal to or smaller than each thickness of the first substance layers in the second multilayer film; and the ratio of the thickness of the layers of the first substance to the thickness of the layers of the second substance in the first multilayer film is different from the ratio of the thickness of the layers of the first substance to the thickness of the layers of the second substance in the second multilayer film, so as to reduce the internal stress of the multilayer film reflective mirror.