To obtain the subject preparation which contains a specific metallic complex as an active ingredient, exerts continuous high antimicrobial activity at a low cost and doesn't easily change color.

This antimicrobial is obtained by including at least one kind of metallic complexes of formula I {M+ is a monovalent alkali metal ion; H+ is hydrogen ion; Y is divalent zinc ion, divalent copper ion or monovalent silver ion; R is a group of formula II [Z is the group of N or -CR3- (R is H or an organic group); R1 and R2 are each an organic group]; (a) is 2 or 3; 0 ≤x, 0≤y, x+y=1}, preferably a metallic complex of formula III, as active ingredients. The silica gel in which a metallic complex of formula I or formula III is adsorbed and holded is preferably included as an active ingredient. The metallic complex of formula I is prepared by treating an anionic metal complex [Y(R)n]1- with a counter cation [M+xH+y]1+ consisting of a monovalent alkali metal ion (M+) and/or hydrogen ion (H+) in a form of complex.