To provide a production method of a protective film having excellent flatness on a substrate having a step.

The production method of a protective film includes steps of: applying a photosensitive resin composition containing a polymer (A), a (meth)acrylic compound (B), a polymerization initiator (C) and a solvent (E) on a rugged substrate to form a coating film; and exposing the coating film formed on a recessed part and a projected part of the rugged substrate through a multi-gradation mask in which the transmittance in a position corresponding to the recessed part is higher than the transmittance in a position corresponding to the projected part. The coating film is exposed through a multi-gradation mask in which the transmittance in a position corresponding to the recessed part is 60 to 100% and the transmittance in a position corresponding to the projected part is 10 to 50%.