A lamp, comprising: a casing, having an opening and an outer surface; an elastic cover, covering the outer surface of the casing; characterized, in that the lamp further comprises a main body, disposed at the casing, the main body comprising: a base plate; a rotating element, pivoted to the base plate and located at the opening; a fastening element, disposed at the base plate; a moving element, having an engaging portion, the moving element being disposed at the base plate and moved between a first position and a second position; a linking-up element, having a first end and a second end, the first end being connected to the rotating element, and the second end being connected to the moving element; and a force member, connected to the moving element, when the force member receives a force, the moving element is moved from the first position to the second position, the engaging portion is engaged with the fastening element, the second end of the linking-up element is moved to the second position with the moving element, the first end of the linking-up element brings the rotating element to rotate away from the base plate, and the rotating element is protruded from the opening and pushes against the elastic cover. a casing, having an opening and an outer surface; an elastic cover, covering the outer surface of the casing; characterized, in that the lamp further comprises a main body, disposed at the casing, the main body comprising: a base plate; a rotating element, pivoted to the base plate and located at the opening; a fastening element, disposed at the base plate; a moving element, having an engaging portion, the moving element being disposed at the base plate and moved between a first position and a second position; a linking-up element, having a first end and a second end, the first end being connected to the rotating element, and the second end being connected to the moving element; and a force member, connected to the moving element, when the force member receives a force, the moving element is moved from the first position to the second position, the engaging portion is engaged with the fastening element, the second end of the linking-up element is moved to the second position with the moving element, the first end of the linking-up element brings the rotating element to rotate away from the base plate, and the rotating element is protruded from the opening and pushes against the elastic cover. a base plate; a rotating element, pivoted to the base plate and located at the opening; a fastening element, disposed at the base plate; a moving element, having an engaging portion, the moving element being disposed at the base plate and moved between a first position and a second position; a linking-up element, having a first end and a second end, the first end being connected to the rotating element, and the second end being connected to the moving element; and a force member, connected to the moving element, when the force member receives a force, the moving element is moved from the first position to the second position, the engaging portion is engaged with the fastening element, the second end of the linking-up element is moved to the second position with the moving element, the first end of the linking-up element brings the rotating element to rotate away from the base plate, and the rotating element is protruded from the opening and pushes against the elastic cover.