A silicon drift detector has an X-ray detection device, an electrode terminal subassembly for electrical connection, a Peltier device, and first and second shields formed between the electrode terminal subassembly and the Peltier device. The first shield is made of a material consisting chiefly of an element having an atomic number smaller than the average atomic numbers of the elements included in the material of the Peltier device. The second shield is made of a material consisting chiefly of an element having an atomic number greater than the atomic numbers of the elements included in the material of the Peltier device