A medical adhesive sheet comprising a support having a laminate structure comprising a non-porous sheet and a porous sheet, and a pressure-sensitive layer comprising an acrylic polymer prepared by polymerizing an alkyl (meth)acrylate as a main component monomer, and an organic liquid component which is compatible with the acrylic polymer, formed on the porous sheet side of the support, the layer being subjected to a crosslinking treatment, wherein the pressure-sensitive adhesive layer is embedded in the porous sheet, reaching the laminate interface between the non-porous sheet and the porous sheet. The medical adhesive sheet has improved anchoring property of its pressure-sensitive adhesive layer to the support while exhibiting a good balance between adhesion to the skin and low irritation to the skin.