A boot for an optical connector ferrule, the boot comprising: a ribbon fiber insertion portion which is internally provided with a single vertical partition portion or a plurality of vertical partition portions configured to section plural groups of ribbon fibers having a lot of optical fiber core wires in their leading ends into a plurality of upper and lower stages and enable the insertion of said plural groups of ribbon fibers; a front opening portion which exposes the optical fiber core wires in the respective leading ends of said inserted ribbon fiber plural groups to a forward outer side; wherein the boot is insertable to a boot insertion opening portion which is formed in a rear end side of the optical connector ferrule, wherein each of rear end portion sides of both upper and lower wall surfaces of the ribbon insertion portion forms an exposure notch portion by being notched at a predetermined length toward an innerside of the ribbon fiber insertion portion while leaving said single vertical partition portion or said plurality of vertical partition portions, a fiber guide of each of said plural groups of ribbon fibers is provided by the rear end portion side of said single vertical partition portion or said plurality of vertical partition portions internally provided in said ribbon fiber insertion portion, the end portion side of said single vertical partition portion or said plurality of vertical partition portions protruding outward from said exposure notch portion of said ribbon fiber insertion portion, wherein said fiber guide is provided with standing guide portions at vertically symmetrical positions in both right and left ends of the fiber guide by being formed into an approximately H-shaped cross section in a rear view while leaving both right and left wall surfaces where said vertical partition portions of said ribbon fiber insertion portion are positioned at a time of forming said exposure notch portion, wherein said boot further comprises an elliptical spring which is attached to the boot for said optical connector ferrule and configured to press said optical connector ferrule at the fitting time and maintaining the fitting, and wherein said standing guide portions are formed so as to bridge over a part in a longitudinal direction of said elliptic spring. a ribbon fiber insertion portion which is internally provided with a single vertical partition portion or a plurality of vertical partition portions configured to section plural groups of ribbon fibers having a lot of optical fiber core wires in their leading ends into a plurality of upper and lower stages and enable the insertion of said plural groups of ribbon fibers; a front opening portion which exposes the optical fiber core wires in the respective leading ends of said inserted ribbon fiber plural groups to a forward outer side; wherein the boot is insertable to a boot insertion opening portion which is formed in a rear end side of the optical connector ferrule, wherein each of rear end portion sides of both upper and lower wall surfaces of the ribbon insertion portion forms an exposure notch portion by being notched at a predetermined length toward an innerside of the ribbon fiber insertion portion while leaving said single vertical partition portion or said plurality of vertical partition portions, a fiber guide of each of said plural groups of ribbon fibers is provided by the rear end portion side of said single vertical partition portion or said plurality of vertical partition portions internally provided in said ribbon fiber insertion portion, the end portion side of said single vertical partition portion or said plurality of vertical partition portions protruding outward from said exposure notch portion of said ribbon fiber insertion portion, wherein said fiber guide is provided with standing guide portions at vertically symmetrical positions in both right and left ends of the fiber guide by being formed into an approximately H-shaped cross section in a rear view while leaving both right and left wall surfaces where said vertical partition portions of said ribbon fiber insertion portion are positioned at a time of forming said exposure notch portion, wherein said boot further comprises an elliptical spring which is attached to the boot for said optical connector ferrule and configured to press said optical connector ferrule at the fitting time and maintaining the fitting, and wherein said standing guide portions are formed so as to bridge over a part in a longitudinal direction of said elliptic spring.