A fusion splicing apparatus comprising: a pair of discharge electrodes (13, 15) discharge-heating end faces (5a, 7a) of a pair of optical fibers (1, 3) for fusion splicing the end faces (5a, 7a) to each other; holding units (17,19) holding the pair of optical fibers (1, 3); V-groove blocks (21, 23) each having a V-groove, the V-groove receiving, positioning, and fixing a part of the optical fiber (1,3) on an end-face side of the holding unit (17, 19); V-groove-block moving mechanisms (33, 35) each configured to move one of the V-groove blocks (21, 23) to shift an axial center of the pair of optical fibers (1, 3) from a virtual straight line joining the pair of discharge electrodes (13, 15) to each other; and holding-unit moving mechanisms (37, 39) each configured to move one of the holding units (17, 19) according to the movements of the V-groove-block moving mechanisms (33, 35) so that the pair of optical fibers (1, 3) are arranged in a linear fashion between the V-groove blocks (21, 23) the axial center of the pair of optical fibers (1, 3) is shifted from the virtual straight line joining the pair of discharge electrodes (13, 15) to each other, the V-groove-block moving mechanisms and holder moving mechanism being driven according to a photographed image data which is obtained by photographing the end faces (5a, 7a) of a pair of optical fibers (1, 3) with a camera, the fusion splicing apparatus being characterised in that the holding-unit moving mechanism (37, 39) includes: a pair of first and second guide faces (41, 43) that cross the moving direction of the holding unit (17, 19); the first guide face being a tilt face tilted with respect to a plane that is orthogonal to the moving direction; a first guide member that is positioned between the pair of guide faces (41, 43), is in contact with the tilt face, and is movable along the plane that is orthogonal to the moving direction; a second guide member (45, 49) that is in contact with the second guide face opposing the tilt face and is movable along the plane that is orthogonal to the moving direction; a drive unit that is adapted to move the guide members (45, 47, 49) along the plane that is orthogonal to the moving direction. a pair of discharge electrodes (13, 15) discharge-heating end faces (5a, 7a) of a pair of optical fibers (1, 3) for fusion splicing the end faces (5a, 7a) to each other; holding units (17,19) holding the pair of optical fibers (1, 3); V-groove blocks (21, 23) each having a V-groove, the V-groove receiving, positioning, and fixing a part of the optical fiber (1,3) on an end-face side of the holding unit (17, 19); V-groove-block moving mechanisms (33, 35) each configured to move one of the V-groove blocks (21, 23) to shift an axial center of the pair of optical fibers (1, 3) from a virtual straight line joining the pair of discharge electrodes (13, 15) to each other; and V-groove blocks (21, 23) each having a V-groove, the V-groove receiving, positioning, and fixing a part of the optical fiber (1,3) on an end-face side of the holding unit (17, 19); V-groove-block moving mechanisms (33, 35) each configured to move one of the V-groove blocks (21, 23) to shift an axial center of the pair of optical fibers (1, 3) from a virtual straight line joining the pair of discharge electrodes (13, 15) to each other; and holding-unit moving mechanisms (37, 39) each configured to move one of the holding units (17, 19) according to the movements of the V-groove-block moving mechanisms (33, 35) so that the pair of optical fibers (1, 3) are arranged in a linear fashion between the V-groove blocks (21, 23) the axial center of the pair of optical fibers (1, 3) is shifted from the virtual straight line joining the pair of discharge electrodes (13, 15) to each other, the V-groove-block moving mechanisms and holder moving mechanism being driven according to a photographed image data which is obtained by photographing the end faces (5a, 7a) of a pair of optical fibers (1, 3) with a camera, the fusion splicing apparatus being characterised in that the holding-unit moving mechanism (37, 39) includes: a pair of first and second guide faces (41, 43) that cross the moving direction of the holding unit (17, 19); the first guide face being a tilt face tilted with respect to a plane that is orthogonal to the moving direction; a first guide member that is positioned between the pair of guide faces (41, 43), is in contact with the tilt face, and is movable along the plane that is orthogonal to the moving direction; a second guide member (45, 49) that is in contact with the second guide face opposing the tilt face and is movable along the plane that is orthogonal to the moving direction; a drive unit that is adapted to move the guide members (45, 47, 49) along the plane that is orthogonal to the moving direction. a pair of first and second guide faces (41, 43) that cross the moving direction of the holding unit (17, 19); the first guide face being a tilt face tilted with respect to a plane that is orthogonal to the moving direction; a first guide member that is positioned between the pair of guide faces (41, 43), is in contact with the tilt face, and is movable along the plane that is orthogonal to the moving direction; a second guide member (45, 49) that is in contact with the second guide face opposing the tilt face and is movable along the plane that is orthogonal to the moving direction; a drive unit that is adapted to move the guide members (45, 47, 49) along the plane that is orthogonal to the moving direction.