Provided is a penile erection assistance tool that can provide a ring body which is capable of maintaining a high degree of airtightness of a container, can be interchanged easily, and feels good to use. This penile erection assistance tool is provided with: a cylindrical container having an insertion opening at one end and an air discharge opening at the other end； and a ring body configured so that an outer circumferential rim thereof is elastically and detachably fitted to the insertion opening of the container, and so that a central hole thereof is introduced into the container, the penis being inserted into the central hole of the ring body and the pressure in the container being reduced by suctioning the air therein out through the air discharge opening while the ring body is fitted around the root of the penis, thereby squeezing the penis, causing blood to pool therein and effecting an erection, wherein: the ring body is configured by two layers of elastic members being stacked together, and is configured so that the elastic members are bonded to one another and extend along the outer circumferential rim, the two layers of elastic members extend while repeatedly contacting and separating from each other at intervals in the portion that is introduced into the container, and the two layers of elastic members are in close contact with each other at the tip； and a protrusion is formed on the elastic members at a position within a prescribed distance from the insertion opening.本發明提供一種陰莖勃起輔助器具，可提供能夠將容器的氣密性保持得高，並且轉移亦容易，且使用感亦良好的環狀體。本發明的陰莖勃起輔助器具包括：圓筒狀的容器，於一端設置插入口，於另一端設置排氣口；及環狀體，以環狀體的外周緣彈性地且能夠裝卸地嵌合於容器的插入口，環狀體的中心孔朝容器的內部突入的方式構成。於將陰莖插入環狀體的中心孔，並藉由環狀體嵌合陰莖的根部的狀態下，自排氣口抽吸容器的內部的空氣來減壓，藉此勒緊陰莖而充血並勃起。環狀體是使兩層的彈性構件重疊來構成。彈性構件於外周緣處相互黏著延伸，於朝容器內的突入部中兩層的彈性構件彼此以空開間隔，一面重覆接觸與分離一面進行延伸，且於前端處相互密接的方式構成，彈性構件在進入容器內的距插入口僅規定距離的位置形成有突起。
