Abstract: A clamping device includes a clamp arm (2), an operating lever (3) for pivotally operating the clamp arm (2), and a toggle mechanism (T) provided in connection with the operating lever (3). The clamp arm (2) is formed with a guide path (2a) that intersects a direction in which the clamp arm (2) pivots so that an output member (9) of the toggle mechanism (T) is guided along the guide path (2a). Accordingly, workpieces (W) of heights that can vary over a wide range of up to several centimeters can be firmly fixed without the necessity of performing a troublesome adjustment operation.