To provide a sealing device capable of sealing a bag body which moves continuously, and is long in a moving direction without temporarily stopping the bag body.

The sealing device includes a pair of bar sealers 31 and 32 arranged to be opposed to each other while putting the bag body therebetween, and a driving mechanism which moves to revolve each of the pair of bar sealers in a horizontal plane while holding a state that the sealing surfaces of the pair of bar sealers are opposed to each other. The driving mechanism moves to revolve each of the pair of bar sealers in a state that the bar sealer is supported to be cantilevered. The driving mechanism includes rotating bodies 60 and 62 which receive outputs from a motor 38 and rotate on the horizontal plane, a cam follower 64 which is attached to the rotating body, a cam 65 with which the cam follower is made to cooperate, and a sealer coupling part 66 which is provided at an opposite side with respect to the cam follower on the rotating body. The shape of the cam is formed so that the cam follower moves along the track of the cam accompanied by the rotation of the rotating body to vary a distance to the sealer coupling part from the center of the rotation of the rotating body while the rotating body rotates, and then the pair of bar sealers are displaced in parallel with the moving direction of a film in a fixed section in a state of being brought into contact with each other.