A photodetecting unit having a favorable attaching operability is provided. In a photodetecting unit 1, two structures for attachment 30 are fixed to the rear face of a supporting substrate 20 formed by a sintered body of a ceramic. In the process of manufacturing the photodetecting unit 1, a laminate of green sheets is fired, so as to form a sintered body of a ceramic, and then each structure for attachment 30 is bonded to the rear face of the supporting substrate 20. This allows the structures for attachment 30 to be arranged accurately on the rear face of the supporting substrate 20, thereby ameliorating the attaching operability of the photodetecting unit 1.
