A sheath removing unit that removes a sheath of a sheathed optical fiber comprising: a sheath removing blade including a pair of blade bodies (4A, 4B) which are disposed so as to face each other and concave blade portions which are formed on each opposite surfaces of the blade bodies; an optical fiber guide disposed so as to be superimposed on the sheath removing blade; and a positioning plate that positions the sheathed optical fiber and that is disposed on the side opposite to the side of the optical fiber guide where the sheath removing blade is positioned, wherein the optical fiber guide includes a first guide body and a second guide body that are disposed so as to face each other, the first guide body includes a first protruding portion which is disposed so as to be superimposed on a first blade body of the blade bodies and protrudes from the opposite surface of a first blade body toward a second blade body when seen in plan view, the second guide body includes a second protruding portion that is disposed so as to be superimposed on the second blade body and protrudes from the opposite surface of the second blade body toward the first blade body when seen in plan view, a lower inclined portion, which is outwardly inclined toward a protruding direction of the first protruding portion, is formed on a surface of the first protruding portion facing the second guide body, an upper inclined portion, which is outwardly inclined toward a protruding direction of the second protruding portion, is formed on a surface of the second protruding portion facing the first guide body, the positioning plate includes a pair of positioning portions disposed so as to face each other, a first positioning portion of the positioning portions is disposed so as to operate integrally with the first guide body, a second positioning portion is disposed so as to operate integrally with the second guide body, and receiving portions, which receive the sheathed optical fiber in a radial direction of the sheathed optical fiber, are formed on opposite surfaces of the first positioning portion and the second positioning portion at positions corresponding to the concave blade portions of the sheath removing blade, respectively, characterized in that: a liquid inlet or a gas inlet, which is opened to a space between the first guide body and the second guide body, is formed at the positioning plate. a sheath removing blade including a pair of blade bodies (4A, 4B) which are disposed so as to face each other and concave blade portions which are formed on each opposite surfaces of the blade bodies; an optical fiber guide disposed so as to be superimposed on the sheath removing blade; and a positioning plate that positions the sheathed optical fiber and that is disposed on the side opposite to the side of the optical fiber guide where the sheath removing blade is positioned, wherein the optical fiber guide includes a first guide body and a second guide body that are disposed so as to face each other, the first guide body includes a first protruding portion which is disposed so as to be superimposed on a first blade body of the blade bodies and protrudes from the opposite surface of a first blade body toward a second blade body when seen in plan view, the second guide body includes a second protruding portion that is disposed so as to be superimposed on the second blade body and protrudes from the opposite surface of the second blade body toward the first blade body when seen in plan view, a lower inclined portion, which is outwardly inclined toward a protruding direction of the first protruding portion, is formed on a surface of the first protruding portion facing the second guide body, an upper inclined portion, which is outwardly inclined toward a protruding direction of the second protruding portion, is formed on a surface of the second protruding portion facing the first guide body, the positioning plate includes a pair of positioning portions disposed so as to face each other, a first positioning portion of the positioning portions is disposed so as to operate integrally with the first guide body, a second positioning portion is disposed so as to operate integrally with the second guide body, and receiving portions, which receive the sheathed optical fiber in a radial direction of the sheathed optical fiber, are formed on opposite surfaces of the first positioning portion and the second positioning portion at positions corresponding to the concave blade portions of the sheath removing blade, respectively, characterized in that: a liquid inlet or a gas inlet, which is opened to a space between the first guide body and the second guide body, is formed at the positioning plate.