A substrate for forming an artificial valve and that allows connective tissue to easily enter a leaflet forming space and can thereby shorten the time required to form a leaflet, and also provides an artificial valve. Specifically, a columnar substrate main body is provided. A plurality of recesses are formed on the outer peripheral surface of the substrate main body. A cover substrate is mounted on the substrate main body. The recesses are covered with the cover substrate to define leaflet forming spaces. An entry opening for connective tissue is defined between an edge of the cover substrate and an outer edge of the recesses. Slits are formed in the cover substrate to allow communication between the leaflet forming spaces and the outside of the substrate. Each slit is formed parallel to the substrate central axis and has a length that extends to the edge of the cover substrate.
