The device for measuring an optical absorption characteristic of a sample according to the present invention comprising a light source, a optical wave-guide having light input surface(s) and light output surface(s) that are opposite to each other, and a light reflecting surface on which a sample to be measured is disposed, through which the light passes and is reflected by a total reflection on the sample, one or more light transmitting means arranged between the light output surface of the optical wave-guide and the light input surface of the optical wave-guide so that the light is again entered into the optical wave-guide, and a processing device which receives the light re-exited from the optical wave-guide through the output surface and detects the optical absorption characteristics of the sample on the basis of the light received, whereby the light which passes through the optical wave-guide is conducted to the optical wave-guide again, the light is again entered the optical wave-guide, and the light is again reflected on the sample (FIG. 1).