NOVELTY - A surface modifying agent comprises a (meth)acrylic polymer having an alkoxysilyl group (I) and ester-type repeating unit (II).    USE - Surface modifying agent is used for two-component surface modifying agent for manufacturing surface-modified base material (all claimed). Uses include but are not limited to glass of motor vehicles, medicine instrument, artificial organ, solar cell panel, liquid crystal display, glass surface processing agent, biocompatible material, optical medium.    ADVANTAGE - The surface modifying agent has excellent hydrophilicity, lipophilicity, oil-repellency, fog prevention property, and self-cleaning property.    DETAILED DESCRIPTION - A surface modifying agent comprises a (meth)acrylic polymer having an alkoxysilyl group of formula: R4-Si(-R3)(-R5)-R6- (I) and ester-type repeating unit of formula: -(C(-R1)(-C(=O)-O-R2)-CH2)- (II).    R1=H or methyl;    R2=hydrophilic group, hydrophobic group, cationic group or anionic group;    R3-R5=1-4C alkyl or 1-4C alkoxy, in which at lest one of R3-R5 is 1-4C alkoxy;and    R6=1-12C alkylene.    INDEPENDENT CLAIMS are included for the following:    (1) surface-modified base material, which is obtained by modifying the surface of a base material using surface modifying agent;    (2) manufacture of (meth)acrylic-type polymer, which involves (meth)acrylic-type monomer of formula: CH2=C(-R1)-C(=O)-O-R2 in presence of alkoxy silyl group-containing compound of formula: R4-Si(-R3)(-R5)-R6-SH;    (3) two-component surface modifying agent, which contains liquid (I) containing silane coupling agent having thiol group and polymer containing alkoxy silyl group, and liquid (II) containing (meth)acryl monomer;    (4) manufacture of surface-modified base material, which involves coating liquid (I) containing silane coupling agent having thiol group and polymer having alkoxy silyl group on base material, coating liquid (II) containing (meth)acryl monomer, and reacting silane coupling agent having thiol group and (meth)acryl monomer;    (5) surface hydrophilizing agent, which comprises (meth)acrylic-type polymer obtained by polymerizing silicon-containing monomer of formula: H2C=C(-R1)-C(=O)-Y'-R6-Si(-R3)(-R5)-R4 and nitrogen-containing monomer of formula: H2C=C(-R1)-C(=O)-Y'-R6-N+(-R9)(-R10)-R8-COO-; and    (6) surface-hydrophilized base material, which has a film containing surface hydrophilizing agent formed on the surface of base material.    Y'=O or NH;    R8=1-4C alkylene;and    R9,R10=H or 1-4C alkyl.