A water-disintegrable sheet in which a base paper sheet is impregnated with an aqueous agent, wherein the base paper sheet has a weight per unit area of 30 to 150 gsm and includes a water-soluble binder, wherein the water-soluble binder is carboxymethyl cellulose and cellulose nanofibers having a fiber width of at least 1 nm and at most 1000, the aqueous agent includes a cross-linking agent which cross-links with a water-soluble binder, the blending ratio of water-soluble binder to cellulose nanofibers is 9:1 to 1:1, in the base paper sheet, content of the water-soluble binder and content of the cellulose nanofibers gradually increase from inside toward outside of the base paper sheet in a thickness direction, and when a wear resistance test is performed three times using a Gakushin type fastness rubbing tester with a PP band as a rubbing finger and an average of measured values for the three times is calculated for each of a MD direction and a CD direction, each average value is at least 40, obtainable by a method comprising the steps of: addition of a solution including a water-soluble binder, wherein the water-soluble binder is carboxymethyl cellulose and cellulose nanofibers having a fiber width of at least 1 nm and at most 1000 to an outer surface of a base paper sheet; drying a sheet to which the solution has been added; and addition of an aqueous agent including a cross-linking agent which cross-links with a water-soluble binder, wherein the water-soluble binder is carboxymethyl cellulose, to the sheet after drying, wherein the concentration of the solution added in the addition of the solution is at least 3.3%, and a blending ratio of the water-soluble binder, wherein the water-soluble binder is carboxymethyl cellulose, to the cellulose nanofibers in the solution is 9:1 to 1:1. the base paper sheet has a weight per unit area of 30 to 150 gsm and includes a water-soluble binder, wherein the water-soluble binder is carboxymethyl cellulose and cellulose nanofibers having a fiber width of at least 1 nm and at most 1000, the aqueous agent includes a cross-linking agent which cross-links with a water-soluble binder, the blending ratio of water-soluble binder to cellulose nanofibers is 9:1 to 1:1, in the base paper sheet, content of the water-soluble binder and content of the cellulose nanofibers gradually increase from inside toward outside of the base paper sheet in a thickness direction, and when a wear resistance test is performed three times using a Gakushin type fastness rubbing tester with a PP band as a rubbing finger and an average of measured values for the three times is calculated for each of a MD direction and a CD direction, each average value is at least 40, obtainable by a method comprising the steps of: addition of a solution including a water-soluble binder, wherein the water-soluble binder is carboxymethyl cellulose and cellulose nanofibers having a fiber width of at least 1 nm and at most 1000 to an outer surface of a base paper sheet; drying a sheet to which the solution has been added; and addition of an aqueous agent including a cross-linking agent which cross-links with a water-soluble binder, wherein the water-soluble binder is carboxymethyl cellulose, to the sheet after drying, wherein the concentration of the solution added in the addition of the solution is at least 3.3%, and a blending ratio of the water-soluble binder, wherein the water-soluble binder is carboxymethyl cellulose, to the cellulose nanofibers in the solution is 9:1 to 1:1. addition of a solution including a water-soluble binder, wherein the water-soluble binder is carboxymethyl cellulose and cellulose nanofibers having a fiber width of at least 1 nm and at most 1000 to an outer surface of a base paper sheet; drying a sheet to which the solution has been added; and addition of an aqueous agent including a cross-linking agent which cross-links with a water-soluble binder, wherein the water-soluble binder is carboxymethyl cellulose, to the sheet after drying, wherein the concentration of the solution added in the addition of the solution is at least 3.3%, and a blending ratio of the water-soluble binder, wherein the water-soluble binder is carboxymethyl cellulose, to the cellulose nanofibers in the solution is 9:1 to 1:1.