PROBLEM TO BE SOLVED: To provide an anastomosis instrument and an anastomosis structure, easily anastomose an inner wall of a side wall end of one blood vessel to an inner wall of a side wall end of the other blood vessel while further suppressing the tissue invasion of the blood vessels than conventional ones.SOLUTION: A first vascular anastomosis instrument 2 and a second vascular anastomosis instrument 3 can hold inner walls vi1 and vi2 of the blood vessels v1 and v2 in the exposed state to outside by sucking from a first suction hole 7 and a second suction hole 8. Accordingly, conventionally performed complicated work requiring skills such as to stick side wall ends ve1 and ve2 of the blood vessels v1 and v2 to needles one by one to be turned outward can be eliminated, and as a result, the inner wall vi1 of the side wall end ve1 of one blood vessel v1 can be easily anastomosed to the inner wall vi2 of the side wall end ve2 of the other blood vessel v2. Further, since the blood vessels v1 and v2 are not penetrated by needles, exposure of a foreign substance to inner lumen surfaces of the blood vessels v1 and v2 can be avoided, and tissue invasion of the blood vessels v1 and v2 can be further suppressed by the anastomosis instruments than conventional ones.
