An endoscope system , comprising: illumination means that includes a light emitting unit, which emits two or more illumination light beams including first illumination light and second illumination light having different wavelength regions, and that irradiates a subject with the first illumination light and the second illumination light; image signal acquisition means being arranged to acquire two or more color signals having different pieces of color information by receiving and imaging return light from the subject using an imaging element; and multi-color image generation means being arranged to generate a multi-color image formed from calculated values obtained by performing predetermined calculation for each pixel using the two or more color signals; characterized by a light amount ratio setting unit , which sets a light amount ratio between the first illumination light and the second illumination light, wherein the illumination means irradiates the subject with illumination light based on the light amount ratio set by the light amount ratio setting unit , and blood vessel extraction image generation means being arranged to generate at least one of a first layer blood vessel extraction image, which is obtained by extracting a first layer blood vessel at a specific depth from the multi-color image, and a second layer blood vessel extraction image, which is obtained by extracting a second layer blood vessel at a position deeper than the first layer blood vessel from the multi-color image, by performing blood vessel extraction processing, which differs depending on the light amount ratio, on the multi-color image. illumination means that includes a light emitting unit, which emits two or more illumination light beams including first illumination light and second illumination light having different wavelength regions, and that irradiates a subject with the first illumination light and the second illumination light; image signal acquisition means being arranged to acquire two or more color signals having different pieces of color information by receiving and imaging return light from the subject using an imaging element; and multi-color image generation means being arranged to generate a multi-color image formed from calculated values obtained by performing predetermined calculation for each pixel using the two or more color signals; a light amount ratio setting unit , which sets a light amount ratio between the first illumination light and the second illumination light, wherein the illumination means irradiates the subject with illumination light based on the light amount ratio set by the light amount ratio setting unit , and blood vessel extraction image generation means being arranged to generate at least one of a first layer blood vessel extraction image, which is obtained by extracting a first layer blood vessel at a specific depth from the multi-color image, and a second layer blood vessel extraction image, which is obtained by extracting a second layer blood vessel at a position deeper than the first layer blood vessel from the multi-color image, by performing blood vessel extraction processing, which differs depending on the light amount ratio, on the multi-color image. <EOS>