A contact lens holding device for vitreous surgery for holding a contact lens for vitreous surgery on an eyeball, comprising: a lens holding ring for holding the contact lens, wherein the lens holding ring comprises: a ring shaped ring body having an opening into which the contact lens for vitreous surgery is inserted; and engagement parts disposed at positions opposed to each other on an outer circumferential part of the ring body across the opening, wherein the engagement parts are configured to engage a one-piece string-like body for fixating the ring body around a cornea at the surface of the eyeball, wherein: the lens holding ring is configured to be fixed on a surface of the eyeball by being pressed against the surface of the eyeball by tensile stress of the string-like body provided in a stretched state when holding the contact lens for vitreous surgery on the eyeball, the string-like body is configured to be laid along a surface of the eyeball with appropriate tensile stress by extending along the lens holding ring and hooking its both ends on at least two support members (21, 23) inserted in the eyeball at opposed positions across the cornea of the eyeball, the outer circumferential part of the ring body is interposed by the string-liked body laid between at least the two support members (21, 22) when holding the contact lens for vitreous surgery on the eyeball, and the engagement parts include protruding pieces (57, 57c, 57d) configured to transmit pressing stress to the ring body for pressing the ring body toward the surface of the eyeball by that the protruding pieces (57, 57c, 57d) receive the tensile stress of the string-like body. a lens holding ring for holding the contact lens, wherein the lens holding ring comprises: a ring shaped ring body having an opening into which the contact lens for vitreous surgery is inserted; and engagement parts disposed at positions opposed to each other on an outer circumferential part of the ring body across the opening, wherein the engagement parts are configured to engage a one-piece string-like body for fixating the ring body around a cornea at the surface of the eyeball, wherein: a ring shaped ring body having an opening into which the contact lens for vitreous surgery is inserted; and engagement parts disposed at positions opposed to each other on an outer circumferential part of the ring body across the opening, wherein the engagement parts are configured to engage a one-piece string-like body for fixating the ring body around a cornea at the surface of the eyeball, wherein: the lens holding ring is configured to be fixed on a surface of the eyeball by being pressed against the surface of the eyeball by tensile stress of the string-like body provided in a stretched state when holding the contact lens for vitreous surgery on the eyeball, the string-like body is configured to be laid along a surface of the eyeball with appropriate tensile stress by extending along the lens holding ring and hooking its both ends on at least two support members (21, 23) inserted in the eyeball at opposed positions across the cornea of the eyeball, the outer circumferential part of the ring body is interposed by the string-liked body laid between at least the two support members (21, 22) when holding the contact lens for vitreous surgery on the eyeball, and the engagement parts include protruding pieces (57, 57c, 57d) configured to transmit pressing stress to the ring body for pressing the ring body toward the surface of the eyeball by that the protruding pieces (57, 57c, 57d) receive the tensile stress of the string-like body.