A cellular electrophysiology sensor is adapted to measure an electrical change of a test cell. A chip for the sensor includes a diaphragm, and a thermally-oxidized film mainly containing silicon dioxide on the diaphragm. The diaphragm includes a silicon layer and a silicon dioxide layer on an upper surface of the silicon layer. A through-hole passing through the silicon layer and the silicon dioxide layer is formed. The through-hole has an opening which opens at the silicon dioxide layer and is adapted to capture the test cell. The thermally-oxidized film is provided on an inner wall surface of the through-hole, and unified with the silicon dioxide layer at the opening of the through-hole. This cellular electrophysiology sensor chip can stably capture the test cell and provides a gigaseal stably even if test cells have different properties.