To provide a basement membrane specimen and artificial tissue which are held adsorbed and fixed onto a plastic surface during the preparation of the basement membrane and the artificial tissue but are formed on a proteinic support temporarily bonded to be made physically peelable from the plastic surface when desired and can be transplanted while maintaining the structure of the basement membrane and are therefore additionally higher in their versatility.

The basement membrane specimen and artificial tissue which can be transplanted while maintaining the structure of the basement membrane are prepared by temporarly bonding the proteinic support on the plastic surface through a hydrophobically bondable adsorption polymer having a linear carbon skeleton having a hydrophobic property and a functional group reactive with protein within the molecule of an alternate copolymer or the like of methyl vinyl ether and maleic anhydride, forming the basement membrane specimen or the artificial tissue thereon and physically peeling the proteinic support carrying and supporting the basement membrane specimen or the artificial tissue from the plastic surface when desired.