A connector, comprising: a cylindrical connector housing having through-holes extending in a circumferential direction formed on right and left; a cylindrical male member including an opposing end with a tapered portion to be entered into an opposing end of the connector housing, and including a circumferential groove conforming with the through-holes in a state wherein the male member enters into the opposing end of the connector housing; and an elastic lock member (13, 25) including an intermediate portion, and right-and-left leg portions (13b, 25b) projecting to right and left from the intermediate portion to be received into the through-holes, wherein sliding inclined surfaces to be engaged with loose ends of the leg portions (13b, 25b) of the lock member (13, 25) are provided on an outer periphery of the connector housing, and the lock member (13, 25) takes an engagement position where the loose ends of the leg portions (13b, 25b) are positioned in proximal positions of the sliding inclined surfaces, and the leg portions (13b, 25b) enter into the circumferential groove inward from the through-holes; and a release position where the loose ends of the leg portions (13b, 25b) are positioned in distal positions of the sliding inclined surfaces, and respectively spread to open the leg portions (13b, 25b) against an elastic force of the lock member (13, 25), and the leg portions (13b, 25b) escape toward the through-holes from the circumferential groove, said connector being characterized in that the loose ends are surrounded by side walls (17a, 17b) from front and back in an axial direction of the connector housing so as to prevent a deformation of the loose ends by an unintended external force and to reliably perform a release operation. a cylindrical connector housing having through-holes extending in a circumferential direction formed on right and left; a cylindrical male member including an opposing end with a tapered portion to be entered into an opposing end of the connector housing, and including a circumferential groove conforming with the through-holes in a state wherein the male member enters into the opposing end of the connector housing; and an elastic lock member (13, 25) including an intermediate portion, and right-and-left leg portions (13b, 25b) projecting to right and left from the intermediate portion to be received into the through-holes, wherein sliding inclined surfaces to be engaged with loose ends of the leg portions (13b, 25b) of the lock member (13, 25) are provided on an outer periphery of the connector housing, and the lock member (13, 25) takes an engagement position where the loose ends of the leg portions (13b, 25b) are positioned in proximal positions of the sliding inclined surfaces, and the leg portions (13b, 25b) enter into the circumferential groove inward from the through-holes; and a release position where the loose ends of the leg portions (13b, 25b) are positioned in distal positions of the sliding inclined surfaces, and respectively spread to open the leg portions (13b, 25b) against an elastic force of the lock member (13, 25), and the leg portions (13b, 25b) escape toward the through-holes from the circumferential groove, said connector being characterized in that the loose ends are surrounded by side walls (17a, 17b) from front and back in an axial direction of the connector housing so as to prevent a deformation of the loose ends by an unintended external force and to reliably perform a release operation.