To prepare a surface protecting film capable of solving problems in a rise in tack by heating the surface protecting film without causing problems in recesses of a material to be protected, inclusion, etc., of bubbles due to the occurrence of fisheyes in the surface protecting film prepared by a coextrusion method.

This surface protecting film is formed by coextruding a tacky agent layer onto one surface of a substrate layer comprising a polyethylene- based resin. In this case, the polyethylene-based resin in the substrate layer has ≤30°C breadth ranging from a temperature at which 10wt.% is eluted to a temperature at which 100wt.% elution is completed when carrying out the elution according to a cross fractionation method, 1.5-3.5 value of weight-average molecular weight/number-average molecular weight and 0.84-0.92g/cm3 density. The tacky agent layer is obtained by mixing an ethylene-vinyl acetate copolymer having 10-47wt.% vinyl acetate content with a polyethylene-based resin of the same kind as that used in the substrate layer so as to provide 8-20wt.% total vinyl acetate content in the whole mixture.