PURPOSE: To provide the absorbance measuring device which can simultaneously measure the quantity of scattered light, the quantity of transmitted light and the quantity of absorbed light sensitively by one device.

CONSTITUTION: The device is equipped with a face shield container 2 housing a transparent container 1 in which tested liquid 10 is contained and with a light source 3 and a photoelectric transfer unit 6 which is disposed in the direction that light from the light source 3 is advanced straight ahead, with the face shield container 2 held in between, and apertures 11, 12 and 13 are provided for the wall of the face shield container 2 over a light path reaching the transparent container 1 from the light source 3, a light path reaching the first photoelectric transfer unit 6 from the transparent container 1, and a light path reaching a second photoelectric transfer unit 8 from the transparent container 1.