A grinding apparatus and a grinding method of a composite substrate including resin, by which loading of a grinding wheel can be suppressed in grinding of a large-sized composite substrate including resin, and with which grinding can be effectively performed with high precision. This method for grinding a front surface of a composite substrate formed with a resin substrate embedded with at least one of a semiconductor device chip and an electrode, includes: bringing at least a part of a grinding member for grinding the front surface of the composite substrate into contact with the front surface; supplying water to at least one of a contacting part or a non-contacting part between the front surface of the composite substrate and the grinding member; and grinding the front surface of the composite substrate simultaneously with the supplying water.