A medication injecting catheter (1, 31, 41) for injecting a medication into a living body through a body wall thereof, the medication injecting catheter (1, 31, 41) comprising: an elongate catheter body (2, 32, 42) including a medication supply lumen defined therein; a tubular body connected to the distal end of the catheter body (2, 32, 42) and having a lumen defined therein which is held in fluid communication with the medication supply lumen; an injection needle connected to a distal end of the tubular body; a hollow cylindrical cover member (9, 43) that includes an inner space defined therein for housing at least the tubular body therein, the cover member (9, 43) being disposed on a distal end portion of the catheter body (2, 32, 42) for reciprocating movement along an axial direction of the catheter body (2, 32, 42) between a first position in which a distal end of the injection needle is housed in the inner space and a second position in which the distal end of the injection needle projects forwardly from the inner space; an opening and closing mechanism that includes an operating member (17, 34, 34A, 34B) rotatable in circumferential directions of the catheter body (2, 32, 42) in the inner space in the cover member (9, 43), for opening and closing the lumen in the tubular body depending on an angular position of the operating member (17, 34, 34A, 34B); a motion converting mechanism for converting the reciprocating movement of the cover member (9, 43) relative to the catheter body (2, 32, 42) into rotary movement of the operating member (17, 34, 34A, 34B) to cause the opening and closing mechanism to close the lumen in the tubular body when the cover member (9, 43) is positioned in the first position and to cause the opening and closing mechanism to open the lumen in the tubular body when the cover member (9, 43) is positioned in the second position; and a resilient member which is disposed between the catheter body (2, 32, 42) and the cover member (9, 43) and which resiliently presses the cover member (9, 43) forwardly of the catheter body (2, 32, 42) toward the first position. an elongate catheter body (2, 32, 42) including a medication supply lumen defined therein; a tubular body connected to the distal end of the catheter body (2, 32, 42) and having a lumen defined therein which is held in fluid communication with the medication supply lumen; an injection needle connected to a distal end of the tubular body; a hollow cylindrical cover member (9, 43) that includes an inner space defined therein for housing at least the tubular body therein, the cover member (9, 43) being disposed on a distal end portion of the catheter body (2, 32, 42) for reciprocating movement along an axial direction of the catheter body (2, 32, 42) between a first position in which a distal end of the injection needle is housed in the inner space and a second position in which the distal end of the injection needle projects forwardly from the inner space; an opening and closing mechanism that includes an operating member (17, 34, 34A, 34B) rotatable in circumferential directions of the catheter body (2, 32, 42) in the inner space in the cover member (9, 43), for opening and closing the lumen in the tubular body depending on an angular position of the operating member (17, 34, 34A, 34B); a motion converting mechanism for converting the reciprocating movement of the cover member (9, 43) relative to the catheter body (2, 32, 42) into rotary movement of the operating member (17, 34, 34A, 34B) to cause the opening and closing mechanism to close the lumen in the tubular body when the cover member (9, 43) is positioned in the first position and to cause the opening and closing mechanism to open the lumen in the tubular body when the cover member (9, 43) is positioned in the second position; and a resilient member which is disposed between the catheter body (2, 32, 42) and the cover member (9, 43) and which resiliently presses the cover member (9, 43) forwardly of the catheter body (2, 32, 42) toward the first position.