To provide an electric tool capable of preventing unfastening of a nut member screwed with a spindle during the operation of a brake device after attaching of an inner member to the spindle.

A grinder 1 is constructed such that a spindle 16 is protruded from a body 10 including a brake device 50, the spindle includes an inner member interfering with pressing members 16A and 16B integrally formed in the spindle to be pressed to the tip side of the spindle following the braking of the spindle by a brake device, a nut member 40 is screwed with the tip of the spindle, and a disc-shaped tool 45 put orthogonally through the spindle is held between the inner member and the nut member. The inner member includes an unfastening prevention member 20 interfering with the pressing parts to be pressed to the disc-shaped tool side during the braking, and an inner flange 30 detachably fixed to the unfastening prevention member to integrally rotate and put through the spindle, and configured to hold the disc-shaped tool with the nut member in the fixed state to the unfastening prevention member.