To easily manufacture a cutting member for a cooling surface and for the separation of solid hydrogen, and at the same time, facilitate the adjusting work at the time of assembly and maintenance.

A cooling surface 11 which is cooled by low temperature helium is formed into a flat plate form. At the same time, a cutting blade 21 which separates solid hydrogen being deposited on the cooling surface 11, is provided at the leading end of a rotating body (rotating shaft 22) of which the rotating center is a straight line being orthogonal to the cooling surface 11, and a cutting part 21a at the leading end of the cutting blade is formed in such a manner that the cutting part 21a may rotate in a plane which is in parallel with the cooling surface 11.