The invention is a biochemical sensing device, including a photodiode capable of sensing the light generated by the reaction made by a specific compound, a specific enzyme, and a luminol as well as converting the optical signal into a current signal. Also, there is a current/voltage converting circuit capable of converting the current signal into an analog voltage signal. In turn, the analog voltage signal can be converted into a digital voltage signal through an analog/digital converter. Finally, by using an electronic device, the digital voltage signal can be received and analyzed, and through the analysis, the amount of the specific compound can be measured. The device of the invention can provide a simple real-time medical assay that can be performed in massive amount. For this reason, the drawbacks of a conventional spectrum analysis instrument of being bulky and expensive can be improved.