A vascular anastomosis device of an aspect of the presently disclosed subject matter can include: a head portion that is provided on a distal side of an insertion portion and is capable of projecting a joining member and a cutting member from a distal surface thereof； an anvil configured to deform the joining member projecting from the head portion at a position where the anvil faces the distal surface of the head portion； and a connection member that can be installed so as to be able to project from and retract into the head portion. The anvil can be connected to the distal end of the connection member. The connection member can be configured to allow, along an axial direction, a portion thereof to be separated and ends of the remaining portion to be joined together.
