a measurement apparatus determines contaminant level of oil by qualitatively measuring the light intensity after the light has transmitted through an oil sample . the apparatus comprises light emitting means for generating light to be provided to the oil sample , a container for storing the oil sample , the container being displaced from the light emitting means by a predetermined distance , light receiving means for detecting the intensity of light transmitted through the oil sample , the receiving means being displaced from the container by a predetermined distance , first light conveyance means for conveying the light generated by the light emitting means as coherent light to the oil sample , second light conveyance means for conveying the light transmitted through the oil sample to the light receiving means , wherein the characteristics of the light emitting means and the light receiving means are controlled so that they do not vary depending on the temperature of the oil sample .