A grinding device includes a dresser head (7) at the front end of a spindle (1), and a dresser tool (8) mounted on the dresser head (7) for dressing the grinder (6). The dresser tool (8) is configured such that while the workpiece (W) is being ground by the grinder (6), the dresser tool (8) is out of contact with the grinder (6), and while the grinder (6) is being dressed by the dresser tool (8), the chuck (3) is out of contact with the grinder (6). Thus it is possible to press the dresser tool (8) against the grinder (6) using relative movement between the spindle (1) and the grinder shaft (4). The dresser head (7) can be rotated by rotating the spindle (1). The grinder (6) can thus be dressed without the need to mount the dresser tool (8) every time the grinder is to be dressed.