A surface treatment agent containing: (A) a water repellent oil repellent polymer having a repeating unit derived from at least one water repellent oil repellent monomer selected from (A1) fluorine-containing monomers and (A2) non-fluorine monomers having a hydrocarbon group with 7-40 carbon atoms; (B) a silicone polymer represented by formula R533Si—O—[—Si(R51)2—O—]a—[—Si(R51)(R52)—O—]b—SiR533 (wherein each R51 group independently represents hydrogen, alkyl having 1-20 carbon atoms, aryl having 6-20 carbon atoms or alkoxy having 1-4 carbon atoms; each R52 independently represents a saturated hydrocarbon group having 23-40 carbon atoms; each R53 independently represents a hydrogen atom, an alkyl group having 1-20 carbon atoms, an aryl group having 6-20 carbon atoms, an alkoxy group having 1-4 carbon atoms or a saturated hydrocarbon group having 23-40 carbon atoms; a represents an integer of 0 or more; b represents an integer of 1 or more; and (a+b) is 10-200); and (C) a liquid medium.