To obtain a quadrant projection measuring device in which a measuring time can be shortened.

A quadrant projection measuring device 10 comprises a command condition input section 1 which outputs a radius of a circular arc command and a feed speed, an acceleration/deceleration parameter input section 3 which outputs an acceleration/deceleration parameter, a measuring route generation section 2 which generates a measuring route including a partial circular arc route of a predetermined length determined from a route according to the circular arc command and including a portion in which a moving direction of at least one feeding shaft is inverted, based on the radius, the feed speed and the acceleration/deceleration parameter, a measuring position command generation section 4 which outputs a position command of a feeding shaft on the basis of the measuring route and the acceleration/deceleration parameter, servo control sections 5, 6 each performing servo control, such that a motor position of the feeding shaft follows up the position command, and an error waveform enlarging section 7 which performs processing for enlarging an error of a quadrature projection portion at the motor position in at least the partial circular arc route on the basis of the motor position.