The antibacterial activity of insoluble pyridinium-type polymers with different structures against Escherichia coli suspended in sterilized and distilled water was investigated by a colony count method. The results show that the antibacterial activity of insoluble pyridinium-type polymers, except for one containing I, is characterized by an ability to capture bacterial cells in a living state by adsorption or adhesion, with the process of capturing bacterial cells being at least partially irreversible. This feature differs from the antibacterial activity of the corresponding soluble polymers, which is characterized by the ability to kill bacterial cells in water. In addition, insoluble pyridinium-type polymers can also capture dead bacterial cells. This implies that insoluble pyridinium-type polymers possess broad prospects for development in new water treatment techniques and whole-cell immobilization techniques.