Abstract: According to an embodiment of the present invention, there is provided a cannula inserter, comprising a cannula, a needle, a first movable body, a second movable body, and a biasing means comprising a first coil spring and a second coil spring in a casing, the needle being able to be moved in the cannula, wherein the first coil spring and the second coil spring each of which is in a compression state before a use are arranged side by side in parallel, the first coil spring is capable of extending in an advance direction of the needle to bias the first movable body, and the second coil spring is capable of extending in a retraction direction of the needle to bias the second movable body, wherein a non-piercing end of the needle is secured to the second movable body, and a non-piercing end of the cannula is configured to be pressed by at least one of the first movable body and the second movable body, wherein the compression state of the first coil spring is released such that the first movable body is biased b