To provide an apparatus for observing exercises of small animals by which various motions are accurately measured in good reproducibility without giving stress to the small animals.

This apparatus for observing exercises of small animals is composed of a frame for placing a case for exercise of the small animal, a vibration-proofing support device capable of converting vibration generated when the small animal's exercises to amplitude movement of each directing axis of vertical direction, horizontal direction an height and having vibration damping characteristics and a detector for vibration. In the apparatus, a vibration signal-receiving sensitivity is improved even when the body weight of the small animal is light by changing a supporting strength of the vibration-proofing support device.