In this paper, we propose a photoelectric biosensor exhibiting instantaneous and simple measurement properties. On the basis of surface plasmon resonance principles, the proposed biosensor capitalizes on the adhesion activity between test fluids and metal films. Attenuated total reflection (ATR) occurs when light permeates metal films, resulting in a fluctuation in light intensity. Thus, the fluid properties can be determined by measuring the intensity of the light that exits the fluid. Because adding chemicals or agents to the proposed biosensor is unnecessary, the properties of the measured sample are unaffected during measurements. The photoelectric biosensor features several advantages such as instantaneous measurement, high sensitivity, high resolution, simple experimental architecture, and low cost.