A fusion splicing device comprising: a connecting section that fusion splices a pair of optical fibers; a first glass clamp part to clamp a glass part that has been removed of a coating of a first optical fiber, the first glass clamp part being provided to an outer side of the connecting section; a first coating clamp part to clamp at least a part of the coating of the first optical fiber, the first coating clamp part being provided to an outer side of the first glass clamp part; a second glass clamp part to clamp a glass part that has been removed of a coating of a second optical fiber, the second glass clamp part being provided to an outer side of the connecting section; a second coating clamp part to clamp at least a part of the coating of the second optical fiber, the second coating clamp part being provided to an outer side of the second glass clamp part; a wind protector cover to cover the connecting section, the first and second glass clamp parts, and the first and second coating clamp parts; a heater to heat a protection sleeve covered on a fusion splice point of the optical fibers that have been fusion spliced with the connecting section wherein the heater has a length from 64 to 68 mm and is adapted to heat the protection sleeve having a length from 60 to 62 mm; and an aligning part that can align fingertips holding the optical fiber, the aligning part being provided to an inner side or to an outer side of the first coating clamp part and to an upper surface of the fusion splicing device inside the wind protector cover, wherein: a distance between the aligning part and the fusion splice point is from 29 to 31 mm and less than a half of the length of the heater. a connecting section that fusion splices a pair of optical fibers; a first glass clamp part to clamp a glass part that has been removed of a coating of a first optical fiber, the first glass clamp part being provided to an outer side of the connecting section; a first coating clamp part to clamp at least a part of the coating of the first optical fiber, the first coating clamp part being provided to an outer side of the first glass clamp part; a second glass clamp part to clamp a glass part that has been removed of a coating of a second optical fiber, the second glass clamp part being provided to an outer side of the connecting section; a second coating clamp part to clamp at least a part of the coating of the second optical fiber, the second coating clamp part being provided to an outer side of the second glass clamp part; a wind protector cover to cover the connecting section, the first and second glass clamp parts, and the first and second coating clamp parts; a heater to heat a protection sleeve covered on a fusion splice point of the optical fibers that have been fusion spliced with the connecting section wherein the heater has a length from 64 to 68 mm and is adapted to heat the protection sleeve having a length from 60 to 62 mm; and an aligning part that can align fingertips holding the optical fiber, the aligning part being provided to an inner side or to an outer side of the first coating clamp part and to an upper surface of the fusion splicing device inside the wind protector cover, wherein: a distance between the aligning part and the fusion splice point is from 29 to 31 mm and less than a half of the length of the heater.