A fibrous cellulose excellent in heat resistance and reinforcing effect on resins, and fibrous cellulose composite resins having high strength. The fibrous cellulose has an average fiber width of 0.1 to 19 µm, has hydroxyl groups substituted with carbamate groups at a rate of substitution of 1.0 to 2.0 mmol/g, and has an average fiber length of 0.10 mm or longer. The fibrous cellulose composite resin contains the fibrous cellulose and a resin.