An endoscope apparatus comprising: an insertion portion having a front end portion having a front end surface, a bending portion, and a tube portion, the bending portion being located between the front end portion and the tube portion; and an illumination device comprising: a light source unit which is configured to emit excitation light; a first optical transmission unit which is configured to guide excitation light from the light source unit; a fluorescent member (22, 41) which is located in the tube portion and is configured to be excited by excitation light to emit illumination light; an illumination light determination unit which is configured to determine the amount of illumination light emitted from the fluorescent member (22, 41) to output a determination signal; and a second optical transmission unit which is configured to guide illumination light from the fluorescent member (22, 41) to the front end surface to be irradiated outside the endoscope apparatus, and an excitation light determination unit which is configured to determine the amount of excitation light emitted from the light source unit, and has a first light sensor and a second light sensor, the first light sensor being a photodiode configured to determine the amount of light substantially having the same wavelength as laser light in excitation light, and the second light sensor being a photodiode configured to determine the amount of light having a wavelength other than the wavelength of laser light in excitation light, wherein the illumination light determination unit is configured to determine the amount of illumination light guided by the second optical transmission unit. an insertion portion having a front end portion having a front end surface, a bending portion, and a tube portion, the bending portion being located between the front end portion and the tube portion; and an illumination device comprising: a light source unit which is configured to emit excitation light; a first optical transmission unit which is configured to guide excitation light from the light source unit; a fluorescent member (22, 41) which is located in the tube portion and is configured to be excited by excitation light to emit illumination light; an illumination light determination unit which is configured to determine the amount of illumination light emitted from the fluorescent member (22, 41) to output a determination signal; and a second optical transmission unit which is configured to guide illumination light from the fluorescent member (22, 41) to the front end surface to be irradiated outside the endoscope apparatus, and an excitation light determination unit which is configured to determine the amount of excitation light emitted from the light source unit, and has a first light sensor and a second light sensor, the first light sensor being a photodiode configured to determine the amount of light substantially having the same wavelength as laser light in excitation light, and the second light sensor being a photodiode configured to determine the amount of light having a wavelength other than a light source unit which is configured to emit excitation light; a first optical transmission unit which is configured to guide excitation light from the light source unit; a fluorescent member (22, 41) which is located in the tube portion and is configured to be excited by excitation light to emit illumination light; an illumination light determination unit which is configured to determine the amount of illumination light emitted from the fluorescent member (22, 41) to output a determination signal; and a second optical transmission unit which is configured to guide illumination light from the fluorescent member (22, 41) to the front end surface to be irradiated outside the endoscope apparatus, and an excitation light determination unit which is configured to determine the amount of excitation light emitted from the light source unit, and has a first light sensor and a second light sensor, the first light sensor being a photodiode configured to determine the amount of light substantially having the same wavelength as laser light in excitation light, and the second light sensor being a photodiode configured to determine the amount of light having a wavelength other than the wavelength of laser light in excitation light,