To provide an impactor of a structure capable of reducing bending moment acting on a base part of a cylindrical ejector.

Bending moment acting on the cylindrical ejector 32 takes on a value acquired by multiplying a vertical component force of reaction R by L2 at a front end position P1 of a first cylinder 33 in Fig (a). An example of comparison is shown in (b), the first cylinder 33 is missing, and the cylindrical ejector 32 is directly supported at a second cylinder 34. A protrusion part is L3. Bending moment acting on the cylindrical ejector 32 takes on a value acquired by multiplying the vertical component force of the reaction R by L3 at a front end position P2 of a second cylinder 34. Bending stress which occurs in the cylindrical ejector 32 is proportional to bending moment. Maximum bending stress which occurs in the cylindrical ejector 32 is therefore smaller in (a) than in (b). Since the bending moment and the bending stress are small, it is possible to thin the walls of the cylindrical ejector 32 and reduce its diameter to reduce its weight.