Abstract: A tarpaulin alarm system triggered by unsnapping a tarpaulin attachment snap from a snap member includes a hollow housing on which the snap member is mounted and a Hall effect sensor arranged proximate the snap member on a printed circuit board contained within the housing for cooperation with a magnet associated with the attachment snap. The housing is preferably cylindrical in shape for easy mounting in a drilled hole. The printed circuit board is connected to a switched power source external to the housing, and may be wired to a suitable alarm indicator, such as an existing horn. The circuitry includes an oscillator-based timer for providing a delay period after triggering during which the system may be reset by re-attaching the attachment snap to the snap member.