An insertion device comprising: - a first magnet array comprising a plurality of magnets placed in an array; a first magnet supporting member adapted to support the first magnet array mounted to the first magnet supporting member; - a second magnet array comprising a plurality of magnets placed in an array and being faced to the first magnet array with a gap (δ) interposed therebetween; - a second magnet supporting member adapted to support the second magnet array mounted to the second magnet supporting member; - a gap driving mechanism for driving the first magnet supporting member and/or the second magnet supporting member in a direction in which the magnet arrays (M1, M2) are faced to each other, in order to change a size of the gap (δ); - a first coupling beam coupled integrally to the first magnet supporting member; - a second coupling beam coupled integrally to the second magnet supporting member; - a driving conjunction mechanism for coupling at least one of the first coupling beam and the second coupling beam to the gap driving mechanism; - a compensation spring mechanism adapted to act in such a direction as to cancel an attractive force acting between the first magnet array and the second magnet array; characterized by - a spring conjunction mechanism for coupling the compensation spring mechanism and the coupling beams to each other, wherein the spring conjunction mechanism includes: a first spring supporting frame coupled, through a first coupling portion, to one of the first coupling beam and the second coupling beam, a second spring supporting frame coupled, through a second coupling portion, to the other one of the first coupling beam and the second coupling beam, and a guide mechanism for guiding relative movement of the first spring supporting frame and the second spring supporting frame, in the direction in which the magnet arrays (M1, M2) are faced to each other, the compensation spring mechanism is mounted to both the first spring supporting frame and the second spring supporting frame and, when the size of the gap (δ) is changed, the first spring supporting frame and the second spring supporting frame move relative to each other in the direction in which the magnet arrays (M1, M2) are faced to each other, so that the compensation spring mechanism operates. - a first magnet array comprising a plurality of magnets placed in an array; a first magnet supporting member adapted to support the first magnet array mounted to the first magnet supporting member; - a second magnet array comprising a plurality of magnets placed in an array and being faced to the first magnet array with a gap (δ) interposed therebetween; - a second magnet supporting member adapted to support the second magnet array mounted to the second magnet supporting member; - a gap driving mechanism for driving the first magnet supporting member and/or the second magnet supporting member in a direction in which the magnet arrays (M1, M2) are faced to each other, in order to change a size of the gap (δ); - a first coupling beam coupled integrally to the first magnet supporting member; - a second coupling beam coupled integrally to the second magnet supporting member; - a driving conjunction mechanism for coupling at least one of the first coupling beam and the second coupling beam to the gap driving mechanism; - a compensation spring mechanism adapted to act in such a direction as to cancel an attractive force acting between the first magnet array and the second magnet array; - a spring conjunction mechanism for coupling the compensation spring mechanism and the coupling beams to each other, the spring conjunction mechanism includes: a first spring supporting frame coupled, through a first coupling portion, to one of the first coupling beam and the second coupling beam, a second spring supporting frame coupled, through a second coupling portion, to the other one of the first coupling beam and the second coupling beam, and a guide mechanism for guiding relative movement of the first spring supporting frame and the second spring supporting frame, in the direction in which the magnet arrays (M1, M2) are faced to each other, a first spring supporting frame coupled, through a first coupling portion, to one of the first coupling beam and the second coupling beam, a second spring supporting frame coupled, through a second coupling portion, to the other one of the first coupling beam and the second coupling beam, and a guide mechanism for guiding relative movement of the first spring supporting frame and the second spring supporting frame, in the direction in which the magnet arrays (M1, M2) are faced to each other, the compensation spring mechanism is mounted to both the first spring supporting frame and the second spring supporting frame and, when the size of the gap (δ) is changed, the first spring supporting frame and the second spring supporting frame move relative to each other in the direction in which the magnet arrays (M1, M2) are faced to each other, so that the compensation spring mechanism operates.