FET type Ca^(2+)sensor(Ca-ISFET) was fabricated by micropool and photolithographic method utilizing photosensitive polymer as membrane materials. When OMR-83 negative photoresist was used as membrane material, it gave good sensitivity by micropool method with dioctyladipate as plasticizer but it could not be used in the photolithographic method. When poly(vinyl butyral), PVB was used as membrane material, it gave relatively high sensitivity (23±0.2 mV/decade) for Ca^(2+) concentration range of 10^(-4)∼10^(-1) mole/ℓ by photolithographic method. PVB also provided good adhesion to the pH-ISFET base device without adhesion promoter pretreatment and any plasticizer.