A medical stent is provided including a longitudinal member which has an internal space that extends along a longitudinal axis and a side opening that is formed on a side surface so as to communicate with the internal space, and allows an insertion member that is inserted into the internal space to move along the longitudinal axis； a flap portion which has an extension portion that extends radially outward from the side surface of the longitudinal member so as to engage with tissue and a fixed portion that is fixed to the longitudinal member, being continuous with the extension portion, and is transformable between an open state in which the extension portion radially extends from the side surface of the longitudinal member and a closed state in which the extension portion extends along the longitudinal axis of the longitudinal member； and a flap radial-expansion prevention portion which at least partially passes through the side opening and allows the insertion member to hold the flap portion in the internal space when the flap portion is in the closed state.
