PROBLEM TO BE SOLVED: To solve the problem that the generation amount of secondary &gamma-rays is large due to the irradiation curing and irradiation by neutrons.SOLUTION: A flow path 2 provided inside a chamber 3 is formed of a carbon material or its compound, preferably a CIP material of graphite particles. A rectification part 1 is connected to this flow path 2. An end part of the rectification part 1 is formed with a nozzle 11, and a discharge port is positioned upper side by a prescribed distance from the same face or the bottom face as the flow path 2. The bottom face of the rectification part is arranged with a thin-plate like liner made of a low activation ferrite steel or a general metal material. Liquid lithium is changed into a film flow and discharged from the discharge port. Proton beams are irradiated from a proton beam incident pipe 4. When the proton beams are irradiated, neutrons are generated at a target region and pass through the flow path 2 and a chamber 3 though being irradiated in all directions, and are sufficiently irradiated downward with some directivity. Consequently, the generation amount of the secondary &gamma rays can be suppressed by forming the flow path 2 using a carbon material or a compound thereof.
