AN OBJECT OF THE PRESENT INVENTION IS TO PROVIDE A METHOD OF FIXING AN ANTIBACTERIAL AGENT, BY WHICH METHOD IT IS POSSIBLE TO IMPART ARTICLES OF A WIDE RANGE OF MATERIALS WITH EXCELLENT ANTIBACTERIAL PROPERTY AND GOOD PERSISTENCE OF ANTIBACTERIAL ACTIVITY. SPECIFICALLY, THE METHOD OF FIXING AN ANTIBACTERIAL AGENT, COMPRISES THE STEPS OF: SUBJECTING A SURFACE OF AN ARTICLE TO A SURFACE TREATMENT OF PROVIDING THE SURFACE WITH OXYGEN-CONTAINING FUNCTIONAL GROUPS； AND THEN SUBJECTING THE ARTICLE TO A TREATMENT USING AN ANTIBACTERIAL AGENT COMPOSITION INCLUDING A SILICON-CONTAINING COMPOUND (A) REPRESENTED BY GENERAL FORMULA (1) BELOW. WHEREIN R1 REPRESENTS A HYDROCARBON GROUP HAVING 6 OR MORE CARBON ATOMS, R2 AND R3 REPRESENT LOWER HYDROCARBON GROUPS, RESPECTIVELY, WHICH HYDROCARBON GROUPS MAY BE THE SAME OR DIFFERENT FROM EACH OTHER, R4 REPRESENTS A DIVALENT LOWER HYDROCARBON GROUP, R5, R6 AND R7 REPRESENT LOWER ALKYL GROUPS OR LOWER ALKOXY GROUPS, RESPECTIVELY, WHICH MAY BE THE SAME OR DIFFERENT FROM EACH OTHER, AND X REPRESENTS A HALOGEN ION OR AN ORGANIC CARBONYLOXY ION, OR ALTERNATIVELY, FIRST TREATING THE ARTICLE BY USING THE ANTIBACTERIAL AGENT COMPOSITION； AND THEN SUBJECTING THE ARTICLE TO A 1-10 GHz MICROWAVE IRRADIATION TREATMENT IN A STATE WHERE THE ANTIBACTERIAL AGENT COMPOSITION REMAINS ON THE SURFACE OF THE ARTICLE.
