Patent ID: 7948746

Claim:
A cover opening/closing device, comprising: a case having an opening part that forms a surrounding of a recessed part; and a cover that is capable of opening/closing the opening part, and has a shaft supported by the case, wherein the cover has a cover main body capable of covering at least a part of the opening part; a shaft side in the vicinity of the shaft; an opposite side that is opposite to the shaft side with the cover main body being interposed therebetween; connecting sides that connect the shaft side and the opposite side; and a sealing member arranged on a peripheral portion of the cover main body and a vicinity thereof, the recessed part has a rib formed at a position such that the rib can sink in the sealing member when the cover main body closes the opening part, and portions of the rib to be engaged with portions of the sealing member positioned in the vicinity of the connecting sides are formed so that a height thereof in a depth direction of the recessed part asymptotically decreases from the shaft side toward the opposite side.