A sensor chip and an electronic device with SPAD pixels each including an avalanche photodiode element. The sensor chip includes a pixel area having an array of pixels, an avalanche photodiode element that amplifies a carrier by a high electric field area provided for the each of the pixels, an inter-pixel separation section that insulates and separates each of the pixels from adjacent pixels, and a wiring in a wiring layer laminated on a surface opposite to a light receiving surface of the semiconductor substrate that covers at least the high electric field area. The pixel array includes a dummy pixel area located near a peripheral edge of the pixel area. A cathode and an anode electric potential of the avalanche photodiode element arranged in the dummy pixel area are the same, or at least one of the cathode and anode electric potential is in a floating state.