A connector, comprising: a cylindrical connector housing comprising a hose connecting portion and a mounting opening opposite axially to the connecting portion, wherein the connector housing has through-holes extending in a circumferential direction and formed on right and left, wherein lock-member guide walls are formed on the right and left at a top portion of the outer periphery of the mounting opening which includes a hollow at a center between the lock-member guide walls; a cylindrical male member including an opposing end to be entered into an opposing end of the connector housing, and 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 including an intermediate portion, and right-and-left leg portions extending to right and left from the intermediate portion to be received into the through-holes, wherein the connector housing further includes sliding inclined surfaces to be engaged with loose ends of the leg portions of the lock member provided on an outer periphery of the connector housing, wherein the lock member takes an engagement position where the loose ends of the leg portions are positioned in proximal positions of the sliding inclined surfaces, and the leg portions enter into the circumferential grooves inward from the through-holes; and a release position where the loose ends of the leg portions are positioned in distal positions of the sliding inclined surfaces, and respectively spread to open the leg portions against an elastic force of the lock member, and the leg portions escape toward the through-holes from the circumferential groove, the lock-member guide walls further including locking walls standing on an outer periphery of the connector housing, the locking walls being disposed right and left from the center of the hollow, and an engagement projection projecting laterally from the locking walls, along an axial direction of the connector housing at both right and left side of the hollow, the engagement projection further comprising a locking portion locking the lock member in the engagement position, the locking portion being provided on an upper surface of the engagement projection relative to the radial direction of the connector housing, wherein the engagement projection is formed to protrude at approximately a right angle from the lock-member guide walls in the direction of the hose connecting portion from the mounting opening side at a portion facing the hollow. a cylindrical connector housing comprising a hose connecting portion and a mounting opening opposite axially to the connecting portion, wherein the connector housing has through-holes extending in a circumferential direction and formed on right and left, wherein lock-member guide walls are formed on the right and left at a top portion of the outer periphery of the mounting opening which includes a hollow at a center between the lock-member guide walls; a cylindrical male member including an opposing end to be entered into an opposing end of the connector housing, and 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 including an intermediate portion, and right-and-left leg portions extending to right and left from the intermediate portion to be received into the through-holes, wherein the connector housing further includes sliding inclined surfaces to be engaged with loose ends of the leg portions of the lock member provided on an outer periphery of the connector housing, wherein the lock member takes an engagement position where the loose ends of the leg portions are positioned in proximal positions of the sliding inclined surfaces, and the leg portions enter into the circumferential grooves inward from the through-holes; and a release position where the loose ends of the leg portions are positioned in distal positions of the sliding inclined surfaces, and respectively spread to open the leg portions against an elastic force of the lock member, and the leg portions escape toward the through-holes from the circumferential groove, the lock-member guide walls further including locking walls standing on an outer periphery of the connector housing, the locking walls being disposed right and left from the center of the hollow, and an engagement projection projecting laterally from the locking walls, along an axial direction of the connector housing at both right and left side of the hollow, the engagement projection further comprising a locking portion locking the lock member in the engagement position, the locking portion being provided on an upper surface of the engagement projection relative to the radial direction of the connector housing, wherein the engagement projection is formed to protrude at approximately a right angle from the lock-member guide walls in the direction of the hose connecting portion from the mounting opening side at a portion facing the hollow.