The microbial treatment solution according to the present invention includes an acidic hypochlorous acid water and a quantum water. The acidic hypochlorous acid water is at a concentration of 0.5 wt % to 5.0 wt % for the total microbial treatment solution, and the quantum water is 90.0 wt % to 99.5 wt % for the total microbial treatment solution. The quantum water is water passed through a quantum water converter, the quantum water converter comprising a container having an inlet and an outlet and plural fragments installed in the container. The fragment is made of austenitic stainless steel or martensitic stainless steel, and the fragment has a regular hexagonal prism shape. The fragment has a hole that penetrates a bottom surface and a top surface of the fragment, the hole is a circular cross section. The fragment has a spiral groove going around an inner surface of the hole at least once, and the fragment is heat-treated. The plural fragments are arranged so that a central axis of the fragments is parallel to each other, and the arrangement is maintained. The arranged plural fragments are positioned between the inlet and the outlet.