To provide a screw and nut having fastening torque display functions by screwing the fastening nut to compress an elastic member and screwing the screw into a counter screw hole by the friction force derived from its compression reaction.

When a main body screw part 12 of a screw main body 11 is threadly engaged with a counter screw and a tool is put on a fastening nut 20 of the screw main body 11 so as to screw the nut therein, the end face 26 of the fastening nut 20 is brought in contact with a disc spring 30. As the fastening nut 20 is screwed further, the disc spring 30 is compressed so that the axial force of the head screw part 13 is enhanced to cause the enlargement of the fastening torque of the fastening nut 20. When the fastening torque of the fastening nut 20 becomes larger than the fastening torque of the main body screw part 12, the main body screw part 12 is screwed into the counter screw. When it is so screwed that a datum mark 22 of the fastening nut 20 is coincided with a prescribed fastening torque scale of a torque scale board 25 fixed to the top part 15 of the screw main body 11, the screw main body 11 is fastened in the counter screw hole by a prescribed torque.