A bolt, comprising a coarse thread screw part with a pitch of (P) formed in an area ranging from the tip part to the specified part of a bolt shaft part and a fine thread screw part with a pitch of (p) (p=P/n, where n is the integer of 2 or more) formed by overlapping on the coarse thread screw part at least through the overall length of the coarse thread screw part of the bolt shaft part or through the area ranging from the tip part of the bolt shaft part to the specified part of the coarse thread screw part, whereby the bolt low in cost, mass-producible, excellent in synchronization of screw crests, high in compressive strength and shearing strength, making hard a nut threaded thereto to be loosened even if a large vibration load is applied thereto, and excellent in tightening force can be provided.