Patent ID: 8811788

Claim:
A multi-core optical fiber which includes plural single-core optical fibers each having a core composed of silica-based glass, and a cladding composed of silica-based glass and provided on an outer periphery of the core, the multi-core optical fiber comprising: an intermediate portion in which the plural single-core optical fibers are integrally held by a resin layer, the plural single-core optical fibers being integrally twisted while being two-dimensionally arranged at predetermined positions on a cross-section orthogonal to a longitudinal direction of the multi-core optical fiber; and a terminal portion in which the plural single-core optical fibers are exposed from the resin layer constituting a part of the intermediate portion and separated from each other, wherein the cladding has a glass surface and the claddings of adjacent single-core optical fibers among the plural single-core optical fibers are fused at the glass surfaces thereof to form an integrated glass body, and wherein the resin layer includes a protective coating protecting side surfaces of the integrated glass body.