The present invention is a bactericide composition that contains: (a) an alkyl or alkenyl amine oxide that has a C7-18 alkyl group or alkenyl group; and (b) a mono- or polyoxyalkylene alkyl or alkenyl amine that has a C8-24 alkyl group or alkenyl group and has an average number of added moles of oxyethylene groups of 1-8.本發明係一種殺菌劑組合物,其含有(a)烷基或烯基之碳數為7以上且18以下之烷基或烯基氧化胺、及(b)烷基或烯基之碳數為8以上且24以下且氧伸乙基之平均加成莫耳數為1以上且8以下之單或聚氧伸烷基烷基或烯基胺。