1. A clamp apparatus in which, by rotation of a pair of clamp arms, a workpiece is clamped between one of the clamp arms and another of the clamp arms, comprising:a body;
a drive unit disposed on the body and which outputs a driving force along an axial direction;
a pair of clamp arms supported rotatably on the body, the clamp arms being arranged face-to-face with each other;
a driving force transmission mechanism, which transmits a driving force of the drive unit to the clamp arms, to thereby cause rotation of the clamp arms;
a cover member disposed detachably with respect to the body, and which covers the drive unit and a portion of the clamp arms; and
an unloading tray disposed inside of the cover member at a position below the clamp arms in the direction of gravity, the unloading tray being removable from the body,
wherein the cover member includes openings through which ends of the pair of clamp arms are inserted.