A method of manufacturing a PDMS sheet that ensures good adhesion, handleability and stability to metal thin films or metal patterns of any desired shape. Given a low-molecular-weight siloxane of a cyclic structure represented by [—Si(CH3)2O—]k where k is an integer of 3 to 20 inclusive, the polydimethylsiloxane sheet has a structure where the content of the low-molecular-weight siloxane at the pattern-formation surface is more than that of the low-molecular-weight siloxane at the base surface, and a spacing between the adjacent metal patterns is variable by deformation of the polydimethylsiloxane sheet.