To provide a grinding device to measure a grinding state of a substrate and grind it with high accuracy at a high yield without lowering a throughput of the grinding device.

This grinding device is formed by a cassette index part 100, a cleaning part 200, a grinding part 300 and a control device for controlling the whole grinding device. Raw wafers are conveyed one by one from a cassette set in the cassette index part to the grinding part 300 and ground by using a grinding pad at a lower end of a grinding arm 311. Ground wafers are conveyed by conveying robots 360, 150 and contained in the cassette C4. The control device makes a wafer surface state measuring tool measure a micro surface state of the wafer and corrects grinding conditions on the basis of the measured data during dressing of the grinding pad.