To propose a cover member which can be used properly for a simple cover lid which is temporarily installed when existing cover lid is repaired, in particular, a cover member which can be used properly for a simple cover lid which can be installed easily and in a short time without influence of rainfalls and fallen snow.

In the cover member Q1 for a simple cover lid constructed so as to cover an opening face in the lid receiving section provided in the opening of a water tank or a water passage, the cover member Q1 is made from sheet materials or plate materials and plate materials comprising one laid on top of another, and the water on top of the cover member Q1 is made flow out on the lower face side of the cover member Q1, and drain plugs 20 for preventing the movement of air between the upper and lower section of the cover member Q1 are also provided in specified space relation.