To provide an angle gauge capable of installing a tool in a grinding wheel and its holder for grinding to right and selected grinding angle and even measuring the ground angle found on the tool.

The angle gauge used for grinding the edge of a sharp edged tool has a frame 1 with a certain length. A freely adjustable first device 2 is arranged at one end of the frame and the first device 2 is intended to be arranged and supported around a grinding wheel S during measurement and during the adjustment the distance between the above end and the surrounding of the grinding wheel is changed. A freely adjustable and freely rotatable second device 7 is arranged at the other end of the frame. To this second device 7, a plane edge 11 extended to around the grinding wheel and touching with a corner edge facing to the first device 2 is provided so as to touch the grinding wheel in the state forming an angle to fix the grinding angle together with the surrounding of the grinding wheel.