The invention relates to a method for manufacturing cellulose carbamate. In the method, an auxiliary agent and urea in solution form and possibly in solid form are absorbed into cellulose, and a reaction between cellulose and urea is carried out in a mixture containing cellulose, a liquid, the auxiliary agent, and urea The absorption of the auxiliary agent and urea into cellulose, and the reaction between the cellulose and the auxiliary agent at least partly are carried out in a working device. According to the invention, it is possible to manufacture cellulose carbamate without ammonia, organic solvents or other auxiliary agents, by using only a small quantity of water as a medium.