The present invention provides a membranous connective tissue-forming substrate on which a membranous connective tissue having a sufficient thickness and strength can be formed and a method for producing a membranous connective tissue by using the substrate. Specifically, a connective tissue-forming section 2 is provided on the surface of the substrate. The connective tissue-forming section 2 is surrounded by a thickness-increasing section 3 to enlarge a membranous connective tissue-forming substrate 1 as a whole. The membranous connective tissue-forming substrate 1 is placed under an environment in which a biological tissue material is present to form a membranous connective tissue on the surface of the substrate. In proportion as the size of the membranous connective tissue-forming substrate 1 increases, the thickness of the membranous connective tissue increases. A surplus portion formed on the surface of the thickness-increasing section 3 is removed from the connective tissue. A membranous connective tissue having an increased thickness and strength can be thus obtained.
