There is provided a seizure prevention bolt capable of preventing seizure caused by oblique insertion as well as seizure caused by invasion of a foreign matter such as a spatter. An incomplete screw portion 12 having an outer diameter d that is larger than an inner diameter D 1 of a female screw 20 and smaller than (D + D 1 )/2 is formed at a front end of a normal screw portion 11 formed in a bolt shaft over one or more pitches, and a vertical groove 14 for cutting out a foreign matter such as a spatter is formed in the incomplete screw portion 12. D in the above expression is a nominal diameter of the bolt.
