A grinding device is provided which includes a dressing mechanism for dressing the grinder which is simple in structure and low in manufacturing cost. The grinding device includes a dresser head (7) provided at the front end of a spindle (1), and a dresser tool (8) mounted on the dresser head (7) for dressing the grinder (6), and the dresser tool (8) is configured such that while the workpiece (W) is being ground by the grinder (6), the dresser tool (8) is kept out of contact with the grinder (6), and while the grinder (6) is being dressed by the dresser tool (8), the chuck (3) is kept out of contact with the grinder (6). Thus it is possible to press the dresser tool (8) against the grinder (6) using the 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 easily dressed by a dressing structure that is simple in structure without the need to mount the dresser tool (8) every time the grinder is to be dressed.