A tool shape measuring apparatus configured to measure a shape of a tool having a plurality of cutting edges in an outer circumference thereof, the apparatus comprising: a light projecting section configured to emit an irradiation light to the tool; a light receiving section disposed opposite the light projecting section across the tool therebetween, the light receiving section being configured to receive the irradiation light through a lens, the light receiving section being set at a position where a contour of the tool is imaged by the lens; a calculation section configured to calculate a contour position of the tool based on a detection signal of the light receiving section; wherein the light receiving section includes a light receiving face perpendicular to an optical axis of the lens, and in the light receiving face, there are disposed a plurality of line sensors arranged in different directions from each other, each line sensor having a plurality of sensor elements arranged in one direction, characterized in that the respective line sensor is disposed across a first area not reached by the irradiation light as being completely blocked by the tool, a second area disposed adjacent the first area and reached by the irradiation light with a portion thereof being blocked, and a third area disposed adjacent the second area and reached by the irradiation light not blocked at all; and that the calculation section is configured to check change occurring in output states of the line sensor associated with rotation of the tool and is configured to specify a contour position of the tool based on a center position in the second area when an image of the cutting edge is focused by the lens on the line sensor and the number of the sensor elements included in the second area becomes minimal. a light projecting section configured to emit an irradiation light to the tool; a light receiving section disposed opposite the light projecting section across the tool therebetween, the light receiving section being configured to receive the irradiation light through a lens, the light receiving section being set at a position where a contour of the tool is imaged by the lens; a calculation section configured to calculate a contour position of the tool based on a detection signal of the light receiving section; wherein the light receiving section includes a light receiving face perpendicular to an optical axis of the lens, and in the light receiving face, there are disposed a plurality of line sensors arranged in different directions from each other, each line sensor having a plurality of sensor elements arranged in one direction, characterized in that the respective line sensor is disposed across a first area not reached by the irradiation light as being completely blocked by the tool, a second area disposed adjacent the first area and reached by the irradiation light with a portion thereof being blocked, and a third area disposed adjacent the second area and reached by the irradiation light not blocked at all; and that the calculation section is configured to check change occurring in output states of the line sensor associated with rotation of the tool and is configured to specify a contour position of the tool based on a center position in the second area when an image of the cutting edge is focused by the lens on the line sensor and the number of the sensor elements included in the second area becomes minimal.