An optical fiber splicing unit, comprising: a mechanical splice which aligns optical fibers (11a, 12a) and puts the optical fibers (11a, 12a) between half-split elements (31, 32) to splice the optical fibers to each other; a splice holder portion which holds the mechanical splice; fixing member guide portions which respectively guide anchoring fixation members that are respectively fixed to the optical fibers (11a, 12a) at two sides of the held mechanical splice; anchoring portions which respectively anchor the anchoring fixation members, the anchoring fixation members being respectively guided by the fixing member guide portions and adapted for advancing the anchoring fixation members; and a first spacer which is configured to restrict the advancement of a first anchoring fixation member by abutting the first anchoring fixation member and is disposed to be configured to retract from a position in which the first spacer abuts the first anchoring fixation member, the anchoring fixation member being adapted for being guided by one fixing member guide portion and the fixing member guide portion also allowing advancing wherein a first optical fiber is fixed to the first anchoring fixation member, when gripping and fixing a tip of the first optical fiber to the mechanical splice in a state where a first anchoring fixation member abuts a first spacer which restricts advancement of the first anchoring fixation member, the first anchoring fixation member is configured to advance toward the mechanical splice by retracting the first spacer, and a bend is configured to be formed in the first optical fiber between the mechanical splice and the first anchoring fixation member by the advancement of the first anchoring fixation member. a mechanical splice which aligns optical fibers (11a, 12a) and puts the optical fibers (11a, 12a) between half-split elements (31, 32) to splice the optical fibers to each other; a splice holder portion which holds the mechanical splice; fixing member guide portions which respectively guide anchoring fixation members that are respectively fixed to the optical fibers (11a, 12a) at two sides of the held mechanical splice; anchoring portions which respectively anchor the anchoring fixation members, the anchoring fixation members being respectively guided by the fixing member guide portions and adapted for advancing the anchoring fixation members; and a first spacer which is configured to restrict the advancement of a first anchoring fixation member by abutting the first anchoring fixation member and is disposed to be configured to retract from a position in which the first spacer abuts the first anchoring fixation member, the anchoring fixation member being adapted for being guided by one fixing member guide portion and the fixing member guide portion also allowing advancing wherein a first optical fiber is fixed to the first anchoring fixation member, when gripping and fixing a tip of the first optical fiber to the mechanical splice in a state where a first anchoring fixation member abuts a first spacer which restricts advancement of the first anchoring fixation member, the first anchoring fixation member is configured to advance toward the mechanical splice by retracting the first spacer, and a bend is configured to be formed in the first optical fiber between the mechanical splice and the first anchoring fixation member by the advancement of the first anchoring fixation member.