A four-bar linkage is provided with an opened position holding mechanism. The opened position holding mechanism includes: an engagement pin which protrudes in a rear end portion of a second hinge arm; a support pin which protrudes in a base end portion of an extending portion of a link bracket; a hook bracket having a central portion which is turnably supported by the support pin; and an urging spring which pulls the hook bracket in one direction with respect to the support pin as the center. The hook bracket includes: a guide surface; and an engagement concave portion to be engaged with the engagement pin. The guide surface hits against the engagement pin in accordance with a lid opening operation, and a hit position therebetween relatively moves in a central direction in accordance with a turn with respect to the support pin as the center performed against the pulling force of the urging spring.