To provide an overturning preventive and theft preventive fixing device and a bolt or a nut for preventing a theft of an automatic vending machine, a parking meter, and a safe.

This device fixes a metal fitting 4 by fastening the bolt 6 to the nut 12 by embedding a collar 11 having the nut 12 inside in concrete. A shape of a head part of the bolt 6 is formed in an umbrella shape having an umbrella-shaped inclined part 5 gently expanding to the periphery of the circumference, and an engaging part 8 of the bolt head part is constituted by having a constricted part 7. When applying torque not less than specific torque, the constricted part 7 for connecting the bolt 6 and the engaging part 8 of the bolt head part is twisted off so that the bolt and the head part engaging part are separated. Thus, the engaging part 8 is separated, only the bolt 3 having the umbrella-shaped inclined part unengaging with a tool remains.