To provide a recovery device for an underwater running body, capable of causing the underwater running boat to surely float up by a light and simple structure.

In a recovery device 5 for an underwater running body 1, which is provided in the underwater boat 1 and adapted to cause the underwater running body 1 to float up and recover the same after traveling in the water, a gas chamber 6 is formed in the underwater running body 1 so as to be freely expanded/contracted by slidable inner and outer cylinders 14 and 15, a gas generator 7 is provided in the gas chamber 6, and a locking means 8 is provided for connecting the inner and outer cylinders 14 and 15 in a position where the gas chamber 6 is contracted during traveling and, after the traveling, releasing the connection by the gas pressure of gas discharged from the gas generator 7.