NOVELTY - Protective film (I) comprises a plastic film (1) and a coating layer (5) on the surface of the plastic film, where the coating layer comprises a binder and cerium oxide particles dispersed in the binder, the cerium oxide particles are dispersed into the binder by using a surfactant comprising a silicon (Si)-oxygen bond and/or a Si-carbon bond, the content of the cerium oxide particles in the coating layer is 10 wt.% or more, the cerium oxide particles have an average particle size of 50 nm or less, and the binder has an average composition.    USE - (I) is useful in a front sheet for a solar cell (claimed). (I) is useful for protecting a flexible solar cell, where the solar cell is e.g. single crystal silicon-based solar cell devices, polycrystalline silicon-based solar cell devices, dye sensitized solar cell devices, organic solar cell devices, and single-junction or tandem-structure amorphous silicon-based solar cell devices.    ADVANTAGE - (I) has high transparency, UV absorption ability, weatherability and flexibility, and high adhesiveness.    DETAILED DESCRIPTION - Protective film (I) comprises a plastic film (1) and a coating layer (5) on the surface of the plastic film, where the coating layer comprises a binder and cerium oxide particles dispersed in the binder, the cerium oxide particles are dispersed into the binder by using a surfactant comprising a silicon (Si)-oxygen bond and/or a Si-carbon bond, the content of the cerium oxide particles in the coating layer is 10 wt.% or more, the cerium oxide particles have an average particle size of 50 nm or less, and the binder has an average composition of formula (R11mSi(OR12)nO(4-m-n)/2).    R11 = methyl, ethyl or phenyl;    R12 = 1-8C alkyl;    m = 0.2-2; and    n = 0.01-3, where m+n is less than or equal to 4.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic view of a layer structure of a protective film.    Plastic film (1)    Organic layer (2)    Inorganic layer (3)    Barrier layer (4)    Coating layer. (5)