Water-decomposable fibrous sheet containing gel compound

A water-decomposable fibrous sheet in which an aqueous solution is infiltrated, comprising:

• water-dispersible fibers having a fiber length of at most 20 mm;
• and
• colloidal silica gelled with an electrolyte contained in the aqueous solution, wherein
• a content of the colloidal silica is from 0.25 g to 25 g in terms of silicic acid anhydride, relative to 100 g of the fibers, and a concentration of the electrolyte is at least 0.2% by mass, wherein
• the electrolyte is at least one compound selected from the group consisting of sodium sulfate, potassium sulfate, zinc sulfate, aluminum sulfate, alum, sodium chloride, calcium chloride, magnesium sulfate, zinc nitrate, potassium chloride, sodium carbonate, sodium hydrogencarbonate, ammonium carbonate, sodium citrate, sodium pyrrolidonecarboxylate, potassium citrate, sodium tartrate, potassium tartrate, sodium lactate, sodium succinate, sodium pantothenate, calcium lactate, and sodium laurylsulfate.