To provide a medical tape base material which can provide a medial tape formed with a printing layer having a good adhesion property on a urethane base film.

This medical tape base material is formed by laminating an acrylic tacky adhesive layer 3 of 50 pm in thickness and release paper 4 on the rear surface of the base material film 1 consisting of a urethane resin of 40 μm in thickness, forming a treating agent layer 2 consisting of 100 pts.wt. synthetic rubber composition consisting of 70 to 90% synthetic rubber (for example, 80 wt.% synthetic rubber consisting of SBR and acrylonitrile copolymer and 30 to 10 wt.% ester resin (for example, 20 wt.%) 45 to 65 pts.wt. (for example, 55 pts.wt.) active amino group graft acrylic resin and laminating the printing layer 5 on the front surface of the treating agent layer 2.