The purpose of the present invention is to provide a belt cover as a piece of horse tack which enables a biological signal acquisition system for horses comprising a plurality of sensors and a processing device to be easily attached to and removed from the body of the horse, and which can stably acquire biological signals during various exercise states of a horse ranging from gentle activity such as standing still and resting to rigorous activity such as running at full speed. The present invention pertains to a cover for a belt worn on the body of a horse, wherein the belt cover is characterized by being equipped with at least (1) a horse body surface–contacting electrode that is for detecting bioelectric signals and comprises a stretchable conductor including silver particle–containing conductive particles and a binder resin and having a sheet resistance of no more than 0.1 Ω□, (2) an electric wire that comprises a stretchable conductor including silver particle–containing conductive particles and
