To provide a rubber boat cover easy to carry around, excellent in the mechanical strength and easiness to be stored, and allowing a rubber boat to be used safely and economically without dropping the mobility.

A cover 1 to protect an air-inflated rubber boat includes a base cloth 4 covering the bottom surface of rubber boat and further to the inside of a doughnut-form circumferential part, and silicone resin 5, 6 is applied to the base cloth 4 whereon a specified amount of plastering fibers is laminated, and an elastomeric material in a band shape is as reinforcement affixed to an appropriate place on the outer surface of the doughnut-form circumferential part. As finishing, a mixture of silicone resin and fine plastering fibers in a proportion of 3:1 is further applied to the surface, or the band-form elastomeric material is obtained from a bicycle tire 3.