32 x 32 pH image sensors were successfully fabricated by using the CCD/CMOS image sensor technique, and real time imaging of a chemical reaction and pH distribution was carried out for the first time. The pH variations by a chemical reaction are observed by 200 ms step (i.e. 5 flames per sec). The pH image sensor was able to take a pH image of mouse stomach successfully. It means that the novel image sensor can be applied to a biomedical and biochemical field.