An endoscope apparatus, comprising: an endoscope including an image pickup unit; a color balance adjustment tool having a fluorescent light generating portion and a correction value display portion which is configured show a correction value (WBCAF) for correcting variation in intensity of the fluorescent light generated by the fluorescent light generating portion, the color balance adjustment tool having a tubular body provided with an aperture portion with a diameter to allow insertion of a distal end portion of an endoscope, and an image processing apparatus including: an image signal input unit for inputting an image signal including an image of fluorescent light picked up by the image pickup unit when the color balance adjustment tool is irradiated with excitation light and an image of reflection light of a light having a wavelength band different from a wavelength band of the excitation light, which is picked up by the image pickup unit when the color balance adjustment tool is irradiated with the light having the wavelength band different from the wavelength band of the excitation light; a control unit for calculating a value of coefficient (WBKAF, WBKR) to change brightness value of the image signal, based on the correction value (WBCAF), a brightness value (WBAF) of the image of fluorescent light and a brightness value of the image of reflection light; and a color balance process unit for performing color balance adjustment by changing the brightness value of the image signal inputted through the image signal input unit, using the coefficient value. an endoscope including an image pickup unit; a color balance adjustment tool having a fluorescent light generating portion and a correction value display portion which is configured show a correction value (WBCAF) for correcting variation in intensity of the fluorescent light generated by the fluorescent light generating portion, the color balance adjustment tool having a tubular body provided with an aperture portion with a diameter to allow insertion of a distal end portion of an endoscope, and an image processing apparatus including: an image signal input unit for inputting an image signal including an image of fluorescent light picked up by the image pickup unit when the color balance adjustment tool is irradiated with excitation light and an image of reflection light of a light having a wavelength band different from a wavelength band of the excitation light, which is picked up by the image pickup unit when the color balance adjustment tool is irradiated with the light having the wavelength band different from the wavelength band of the excitation light; an image signal input unit for inputting an image signal including an image of fluorescent light picked up by the image pickup unit when the color balance adjustment tool is irradiated with excitation light and an image of reflection light of a light having a wavelength band different from a wavelength band of the excitation light, which is picked up by the image pickup unit when the color balance adjustment tool is irradiated with the light having the wavelength band different from the wavelength band of the excitation light; a control unit for calculating a value of coefficient (WBKAF, WBKR) to change brightness value of the image signal, based on the correction value (WBCAF), a brightness value (WBAF) of the image of fluorescent light and a brightness value of the image of reflection light; and a color balance process unit for performing color balance adjustment by changing the brightness value of the image signal inputted through the image signal input unit, using the coefficient value.