A reinforcement sleeve heating device configured to heat a reinforcement sleeve put on a connecting site to shrink the reinforcement sleeve in order to reinforce the connecting site of optical fibers fusion-spliced to each other, the reinforcement sleeve heating device comprising: a heating element forming a housing space, the housing space extending in a predetermined direction, the housing space being opened in one direction intersecting with the predetermined direction, the housing space being capable of disposing the reinforcement sleeve; and a cover disposed at a position at which at least a part of the opening of the housing space is covered, wherein the cover includes a contact surface configured to be brought into contact with the reinforcement sleeve in a direction of pushing the reinforcement sleeve into an inside of the housing space when the reinforcement sleeve is disposed in the housing space; wherein a position of the contact surface of the cover is variable in the pushing direction; wherein the cover has a contact member including the contact surface, the contact surface being formed on the bottom part of the contact member, a retaining member configured to retain the contact member, and two springs provided on the retaining member, the springs being configured to act elastic force on the contact member in the pushing direction; wherein the contact member presents a box shape extending in the long-side direction of the housing space and opened on the opposite side of the housing space; characterized in that on the back surface of the bottom part on the opposite side of the contact surface, two spring holders are provided, each spring holder individually retaining one end part of a respective one of the two springs. a heating element forming a housing space, the housing space extending in a predetermined direction, the housing space being opened in one direction intersecting with the predetermined direction, the housing space being capable of disposing the reinforcement sleeve; and a cover disposed at a position at which at least a part of the opening of the housing space is covered, wherein the cover includes a contact surface configured to be brought into contact with the reinforcement sleeve in a direction of pushing the reinforcement sleeve into an inside of the housing space when the reinforcement sleeve is disposed in the housing space; wherein a position of the contact surface of the cover is variable in the pushing direction; wherein the cover has a contact member including the contact surface, the contact surface being formed on the bottom part of the contact member, a retaining member configured to retain the contact member, and two springs provided on the retaining member, the springs being configured to act elastic force on the contact member in the pushing direction; wherein the contact member presents a box shape extending in the long-side direction of the housing space and opened on the opposite side of the housing space; characterized in that on the back surface of the bottom part on the opposite side of the contact surface, two spring holders are provided, each spring holder individually retaining one end part of a respective one of the two springs.