To provide a gas suction amount confirmation device with which a slight gas amount sucked into a device for generating fine bubbles is confirmed and adjusted and to provide a fine bubble generator with which a large amount of fine bubbles are generated in the liquid phase of a river, a fresh fish carrying vehicle and a gas-liquid reaction vessel and the clogging of reactants and filth is prevented.

This gas suction amount confirmation device passes through a gas sucked into the fine bubble generator for jetting liquid in which the gas is mixed and generating the fine bubbles in the liquid phase, and is provided with an at least partially transparently formed container part storing the liquid, a gas flow-out part opened at the sidewall upper part or top plate of the container part, and a gas flow-in part opened at the sidewall lower part or bottom plate of the container part.