To provides a preparation method of the surface holding antimicrobial property, wherein an excellent method improving faults of multi-step production of the prior art and inconveniences of handling and increasing convenience in use is provided.

Polyvinylpyridine and a halogenated hydrocarbon or a halogenated hydrocarbon silane are reacted, to complete, in one step, synthesis of a polymer antibacterial agent having a quarternary ammonium structure, and surface treatment with the polymer antibacterial agent is simply performed by a general coating method.