To prevent the whole face from being injured by scattered metallic pieces in metal working, and to improve working efficiency and convenience in installation and carrying.

This safety device 2 for machinery is composed of a transparent plate 3 having an area suitable for covering a worker's face, a box-type magnet switch box 5 capable of generating and eliminating magnetic field by ON/OFF of a switch 6, and attracting this safety device 2 on a metallic working table 1 in a case when the magnetic field is generated by turning on the switch, reinforcement plates 7a, 7b for integrally mounting the magnet switch box 5 on the transparent plate 3, and a grip 16 for mounting the safety device 2 on the working table 1 or demounting the same from the working table 1.