When a semiconductor sensor element used for detecting high-energy x-rays and gamma rays and an amplifier are connected via wires, the capacitances vary depending on the wires, thereby causing a sensitivity variation. To solve this, a structure for making the capacitances uniform is proposed.If a staggered arrangement is used for high resolution, the capacitances by wiring are different from element to element, so dummy sensor mounting sections (2) are provided to electrode sections (3) to make the capacitance uniform. The width of the connection section is decreased depending on the wiring length so as to make the capacitance uniform.