Medical devices are provided comprising a spike including proximal and distal ends, and a central axis extending from the proximal to the distal end； a valve body； a biasing body which biases the valve body； a distal tube that moves integrally with the valve body to both sides in the axial direction relative to the spike； a proximal tube fixed in the axial direction relative to the spike, the distal tube comprising a guided portion guided toward the proximal tube, and an engagement control unit which moves the guided portion toward one side in the radial direction by connection of the different medical device to the distal tube allowing the guided portion to engage with the proximal tube, and moves the guided portion toward the other side in the radial direction releasing engagement with the proximal tube when the different medical device is detached from the distal tube.
