An electrolysis water-making apparatus for making electrolysis water by electrolyzing a raw material solution including a chlorine ion, the electrolysis water-making apparatus comprising: an electrolytic cell; a raw material solution feed pump used to supply the raw material solution to the electrolytic cell; a raw material solution pipe (32,36) connecting an outlet of the raw material solution feed pump allowing the raw material solution to be discharged therefrom and an inlet of the electrolytic cell allowing the raw material solution to flow thereinto; an electrolyzed solution advection-deterring portion formed in the raw material solution pipe between the outlet and the inlet and configured to prevent the electrolyzed solution from being advected from the electrolytic cell into the raw material solution pipe, a dilution water pump used to supply dilution water used to dilute the raw material solution so that the raw material solution has a predetermined electrolyte concentration; a dilution water pipe (34,36) connecting a second outlet of the dilution water pump allowing the dilution water to be discharged therefrom and a second inlet of the electrolytic cell allowing the dilution water to flow thereinto; and a second electrolyzed solution advection-deterring portion formed in the dilution water pipe between the second outlet and the second inlet and configured to prevent the electrolyzed solution from being advected from the electrolytic cell into the dilution water pipe, wherein the raw material solution feed pump is provided so that the outlet is disposed on an upper side of the inlet, wherein a downward slope pipeline in which an end thereof near the inlet is disposed on an upper side of another end thereof near the outlet is provided in at least a part of the electrolyzed solution advection-deterring portion, wherein the dilution water pump is provided so that the second outlet is disposed on a lower side of the second inlet, and wherein an upward slope pipeline in which an end thereof near the second inlet is disposed on a lower side of another end thereof near the second outlet is provided in at least a part of the second electrolyzed solution advection-deterring portion. an electrolytic cell; a raw material solution feed pump used to supply the raw material solution to the electrolytic cell; a raw material solution pipe (32,36) connecting an outlet of the raw material solution feed pump allowing the raw material solution to be discharged therefrom and an inlet of the electrolytic cell allowing the raw material solution to flow thereinto; an electrolyzed solution advection-deterring portion formed in the raw material solution pipe between the outlet and the inlet and configured to prevent the electrolyzed solution from being advected from the electrolytic cell into the raw material solution pipe, a dilution water pump used to supply dilution water used to dilute the raw material solution so that the raw material solution has a predetermined electrolyte concentration; a dilution water pipe (34,36) connecting a second outlet of the dilution water pump allowing the dilution water to be discharged therefrom and a second inlet of the electrolytic cell allowing the dilution water to flow thereinto; and a second electrolyzed solution advection-deterring portion formed in the dilution water pipe between the second outlet and the second inlet and configured to prevent the electrolyzed solution from being advected from the electrolytic cell into the dilution water pipe, wherein the raw material solution feed pump is provided so that the outlet is disposed on an upper side of the inlet, wherein a downward slope pipeline in which an end thereof near the inlet is disposed on an upper side of another end thereof near the outlet is provided in at least a part of the electrolyzed solution advection-deterring portion, wherein the dilution water pump is provided so that the second outlet is disposed on a lower side of the second inlet, and wherein an upward slope pipeline in which an end thereof near the second inlet is disposed on a lower side of another end thereof near the second outlet is provided in at least a part of the second electrolyzed solution advection-deterring portion.