To provide a living fish counting method and its device which can mechanize living-fish counting operation by using an inexpensive living-fish counting device with rich flexibility while actualizing space saving.

The living-fish counting method has a stage for catching living fishes by a proper method, a stage for selecting normal fishes from the caught living fishes, a stage for putting a counting means for counting the selected normal fishes as they pass in the hollow part of a hollow body having openings at both the ends, and a stage for moving the normal fishes to a water tank (fish preserve) capable of storing living fishes through the hollow body. The living-fish counting device is equipped with the hollow body characterized by that its large-diameter end is opened to the water surface and the other small- diameter end which is made small enough to disable fishes from the large- diameter end to pass one over the other and can be dipped in the water and fittings for fitting the hollow body to the water tank detachably.