To relatively quickly treat even a large number of jellyfishes at a low cost.

A plurality of jellyfish treatment tanks 6a, 6b, 6c, 6d are disposed. A controller 5 controls to avoid flowing-in of additional jellyfishes, for example, in the midst of drying, by sequentially changing the jellyfish treatment tank 6a (6b, 6c, 6d) into which the jellyfishes are to be thrown so as to cyclically execute throwing→drying→ residual cleaning→throwing of the jellyfishes in the same jellyfish treatment tank 6a (6b, 6c, 6d).