The illumination unit (20) of the endoscope apparatus (10) has at least one maximum wavelength that takes at least one maximum value with respect to the light absorption spectrum of the diagnosis target substance existing in the observation body (O), and blue Enhanced wavelength region including at least one of the color region maximum wavelength that takes the maximum value of the color region that is the maximum value of the light absorption spectrum in any one of the three color regions of the region, the green region, and the red region And a laser light source (44-1； 44-3； 44-5) that emits a first enhanced narrowband light including a peak wavelength or a center wavelength, and a wavelength not including the enhanced wavelength region of the three color regions. A laser light source (44-2； 44-4； 44-6) that emits a first non-enhanced narrowband light whose peak wavelength or center wavelength is included in the non-enhanced wavelength region, which is a region, and a first enhanced narrow Band light and first non-emphasized narrow band A light amount ratio changing unit for changing the first light intensity ratio is a quantity ratio of the light (72), the.内視鏡装置（１０）の照明部（２０）は、観察体（Ｏ）に存在する診断対象物質の光吸収スペクトルに対して、少なくとも１つの極大値をとる少なくとも１つの極大波長、及び、青色領域、緑色領域、及び赤色領域の３つの色領域のうち何れかの色領域における光吸収スペクトルの最大値である色領域最大値をとる色領域最大波長、の少なくとも一方を１つ含む強調波長領域に、ピーク波長または中心波長が含まれる第１の強調狭帯域光を出射するレーザ光源（４４－１；４４－３；４４－５）と、上記３つの色領域の強調波長領域を含まない波長領域である非強調波長領域に、ピーク波長または中心波長が含まれる第１の非強調狭帯域光を出射するレーザ光源（４４－２；４４－４；４４－６）と、第１の強調狭帯域光と第１の非強調狭帯域光との光量比である第１の光量比を変更する光量比変更部（７２）と、を有する。
