PURPOSE: To provide the machining method using an abrasive grain fluid capable of largely changing the machining condition without changing the blending of the medium and abrasive grains of the abrasive grain fluid.

CONSTITUTION: An abrasive grain fluid F containing a medium M largely changed with viscosity by temperature and abrasive grains P is used in this machining method. The temperature of the abrasive grain fluid F is controlled by temperature control means 20, 22, 30 to give the viscosity corresponding to the required machining condition to the medium M, and the abrasive grain fluid F gets the fluidity corresponding to the machining condition. The temperature-controlled abrasive grain fluid F is fed to the machining portion 42 of a work 40 while its flow is controlled by a flow control unit 4. The abrasive grain fluid F is continuously brought into contact with the machining portion 42 with the preset fluidity and the preset flow, and the work 40 is machined by the polishing force of the abrasive grains P. The machining condition at this time is made the preset machining condition determined by the fluidity and flow of the abrasive grain fluid F.