It is to provide a torque driver capable of bringing a marker into direct contact with a surface of a fastener member such as a screw to perform marking.A torque driver 1 is configured such that a case 10 is rotated relative to a main shaft 20 when a tightening force applied to the case 10 is transmitted to the main shaft 20 through a torque limiter section 30 and a tightening torque on a screw 80 engaged with a bit 70 attached to a coupler 60 fixed at a tip portion of the main shaft 20 reaches a torque value set in the torque limiter section 30. The torque driver 1 includes: a marker 54 extending from an inside of the coupler 60 to a tip portion of the bit 70 along a side surface of the bit 70; and a marker activating section 40 that allows the marker 54 to move forward by utilizing rotation of the case 10 relative to the main shaft 20 so that a marker tip portion 53 is brought into contact with the screw 80 to perform marking.