To provide a screw thread allowing to disassemble a screwed member in a short time.

This screw thread is provided with a screw thread main body 5 having a first head part 52 provided with a recessed part to be engaged with a screwdriver, a second head part 53 having a polygonal outer peripheral surface 53a to be engaged with a tool and for surrounding the periphery of the first head part 52 through an annular groove 56 provided in the axial direction, and a connecting part 57 sized to form the minimum cross section between the first head part 52 and the second head part 53. When the second head part 53 is fastened by the predetermined fastening torque or more, the connecting part 57 is broken to separate the second head part 53 from the screw thread main body 5.