To provide a fluid processing device that does fluid processing efficiently yet simple and at lower cost, by causing the fluid to enter agitated state with molecular motion activation and irradiating a-rays, which are radiated by a-ray Radiator (2) to the fluid, by means of the molecular motion accelerator. A Fluid Processing Device (1) does the fluid processing with a set of a-ray Radiator, equipped with a-ray radiation material that radiates a-rays in the inner side of Processor Tube (4), with the flow-route of the fluid in the internal space from fluid Inlet (14) towards Outlet (16) and by causing ionization after radiating a-rays to the fluid. The structure of Fluid Processing Device (1) comprises of Molecular Motion Accelerator (3), which activates the molecular motion of the fluid in above-mentioned Processor Tube (4) and does the fluid processing by radiating a-rays to the fluid on which molecular motion activation is done using a molecular motion accelerator, as shown in Figure 4.
