MEASURING METHOD AND GRINDING MACHINE

In a measuring method in which a sizing device is activated only for a prescribed measurement time (t1) to carry out measurement in a main process that is repeated with a period of a prescribed process time (t0), there are stored an activation drift that is a drift of a measured value after activation of the sizing device and a deactivation drift that is a fluctuation in drifts among different elapsed times, each of the drift being measured when the sizing device is activated after a predetermined time has elapsed since the sizing device is deactivated. A measurement drift section is determined. In the measurement drift section, the minimum value and the maximum value of the drift in the measurement time (t1) in the activation drift are equal to the minimum value and the maximum value of the drift within a time (t2) obtained by subtracting the measurement time (t1) from the process time (t0) in the deactivation drift, and the difference between maximum value and the minimum value is equal to or smaller than a prescribed value (E). The sizing device (10) is warmed up for a time (tD) corresponding to a time from activation in the activation drift to the time at which the measurement drift section starts, and then the main process is started.