1. A fusion splicing apparatus for fusion splicing end portions of optical fibers by butt discharging, characterized by comprising: an image observing mechanism for observing the end portions of the optical fibers; an image processing section for measuring a parameter data of a brightness distribution waveform of optical fiber in cross section from a picked up image; a fuzzy operation section for obtaining a degree of attribution for the measured parameter data from a fuzzy operation data registered in advance in a data registering section and identifying the type of optical fiber through a fuzzy operation; a collating section for collating the identified type of optical fiber with fusion splicing conditions for each type of optical fiber registered in advance in a fusion splicing condition registering section; a display unit for displaying the collation result; a fusion splicing mechanism; and a control section.