The HPD (Hybrid Photo-Detector) is a new vacuum photo-detector including a photocathode and an avalanche diode. The HPD provides a gain of more than 1000 in a single multiplication process called 'electron bombardment multiplication'. The photoelectrons from the photocathode are accelerated by a strong electric field to hit the avalanche diode and release a large number of electron-hole pairs corresponding to the acceleration energy. This excellent first multiplication process enables the HPD to achieve excellent multi-photon energy resolution. This first multiplication process is followed by the second avalanche mode multiplication to provide sufficient gain for a variety of applications. H8236 is an HPD module, containing high voltage power supplies and a pre-amplifier.