Abstract: Bolt device for connecting a first component formed with a hole extending therethrough to a second component which is formed with a recess threaded to receive the bolt. The hole has three portions, namely a first shallow portion of large diameter which is an undercut of the end wall of the first component, a second shallow portion eccentric to the first shallow portion, the first component having a lateral groove connecting with the shallow portions, and an elongated recess portion having a smaller diameter than that of the first shallow portion and being coaxial to the first shallow portion. A cup-shaped member surrounds the head of the bolt to prevent rotation of the bolt, and has a disc-shaped base receivable in the undercut and a projection receivable in the lateral groove to prevent rotation of the cup and the bolt relative to the threaded component.