Super-Kamiokande is the world's largest underground type neutrino detector. In order to capture the neutrino which is very difficult to observe, a huge tank with a height of 41.4 m and a diameter of 39.3 m was built to a depth of 1000 m underground. On the inside of the tank there are 11,129 photomultiplier tubes with high sensitivity photosensors and filled with about 50,000 tons of ultra pure water.