A workpiece cutting method of cutting a workpiece having a front side on which a plurality of crossing division lines are formed to define a plurality of separate regions where a plurality of devices are each formed is disclosed. The workpiece cutting method includes a workpiece cutting step of cutting the workpiece held on a first chuck table along the division lines by using a cutting blade, a dummy wafer cutting step of cutting a dummy wafer held on a second chuck table by using the cutting blade, a dummy wafer imaging step of imaging a cut groove formed on the dummy wafer in the dummy wafer cutting step, by using an imaging unit to thereby obtain a detected image, and a determining step of determining the condition of the cutting blade from the condition of chippings formed on both sides of the cut groove in the detected image.