A thread fixing tool (1B, 1C, 1E) for fixing a suture thread passing through a biological tissue, comprising: a first member (2B, 2C, 2E) having a lumen (5B, 5C, 5D) for passing the suture thread therethrough and a communication path (9, 9E), wherein the lumen (5B, 5C, 5D) extends in a central axial direction of the first member (2B, 2C, 2E) and has first opening portions formed in both end surfaces in the central axial direction of the first member (2B, 2C, 2E), and wherein the communication path (9, 9E) has a second opening portion formed at different position with the first opening positions and opened at an end surface or a circumferential surface and an end in communication with an intermediate portion of the lumen (5B, 5C, 5D); and a second member (10B, 10C, 10E) having a shaft portion which is configured to be inserted into the communication path (9, 9E) of the first member (2B, 2C, 2E), and a pressing portion (4b, 4C, 4E) which is formed at a distal portion of the shaft portion, wherein: the pressing portion (4B, 4C, 4E) is configured to be guided to the intermediate portion of the lumen (5B, 5C, 5D) through the communication path (9, 9E) when the shaft portion is inserted into the communication path (9, 9E), and the pressing portion (4B, 4C, 4E) is configured to be inserted into the lumen (5B, 5C, 5D) and to deform outwardly in a radial direction of the shaft portion crossing the central axial direction of the first member (2B, 2C, 2E) for pushing the suture thread against an inner wall of the lumen (5B, 5C, 5D) extending in the central axial direction of the first member (2B, 2C, 2E) when the shaft portion is inserted into the communication path (9, 9E). a first member (2B, 2C, 2E) having a lumen (5B, 5C, 5D) for passing the suture thread therethrough and a communication path (9, 9E), wherein the lumen (5B, 5C, 5D) extends in a central axial direction of the first member (2B, 2C, 2E) and has first opening portions formed in both end surfaces in the central axial direction of the first member (2B, 2C, 2E), and wherein the communication path (9, 9E) has a second opening portion formed at different position with the first opening positions and opened at an end surface or a circumferential surface and an end in communication with an intermediate portion of the lumen (5B, 5C, 5D); and wherein the lumen (5B, 5C, 5D) extends in a central axial direction of the first member (2B, 2C, 2E) and has first opening portions formed in both end surfaces in the central axial direction of the first member (2B, 2C, 2E), and wherein the communication path (9, 9E) has a second opening portion formed at different position with the first opening positions and opened at an end surface or a circumferential surface and an end in communication with an intermediate portion of the lumen (5B, 5C, 5D); and a second member (10B, 10C, 10E) having a shaft portion which is configured to be inserted into the communication path (9, 9E) of the first member (2B, 2C, 2E), and a pressing portion (4b, 4C, 4E) which is formed at a distal portion of the shaft portion, wherein: the pressing portion (4B, 4C, 4E) is configured to be guided to the intermediate portion of the lumen (5B, 5C, 5D) through the communication path (9, 9E) when the shaft portion is inserted into the communication path (9, 9E), and the pressing portion (4B, 4C, 4E) is configured to be inserted into the lumen (5B, 5C, 5D) and to deform outwardly in a radial direction of the shaft portion crossing the central axial direction of the first member (2B, 2C, 2E) for pushing the suture thread against an inner wall of the lumen (5B, 5C, 5D) extending in the central axial direction of the first member (2B, 2C, 2E) when the shaft portion is inserted into the communication path (9, 9E). the pressing portion (4B, 4C, 4E) is configured to be guided to the intermediate portion of the lumen (5B, 5C, 5D) through the communication path (9, 9E) when the shaft portion is inserted into the communication path (9, 9E), and the pressing portion (4B, 4C, 4E) is configured to be inserted into the lumen (5B, 5C, 5D) and to deform outwardly in a radial direction of the shaft portion crossing the central axial direction of the first member (2B, 2C, 2E) for pushing the suture thread against an inner wall of the lumen (5B, 5C, 5D) extending in the central axial direction of the first member (2B, 2C, 2E) when the shaft portion is inserted into the communication path (9, 9E).