In this study, light addressable potentiometric sensors (LAPSs) that have devices with Si3N4/SiO2/Si and Ta2O5/SiO2/Si structures were fabricated. We investigated the response characteristics of penicillin and evaluated the possibile application to a bioimage sensor using the fabricated LAPSs. Penicillinase was immobilized on the devices to hydrolyze the penicillin using the self-assembled monolayer (SAM) method. Then, the response characteristics according to the concentration of the penicillin were measured and compared. The measuring system made up of parts such as a potentiostat, signal processing parts, and an xyz stage controlling part was simplified using LabVIEW. As a result of the enzyme reaction, the sensitivity of the sensor that has a Si3N4 surface was 60 mV/decade and 74 mV/decade which has a Ta2O5 surface in the penicillin concentration range of 0.1–10 mM. Also, we could obtain an image of with a resolution of 128 × 128 pixels within a 1 × 1 cm sensing area.