To provide a manufacturing process of cellulose ethers which gives cellulose ethers having a high degree of substitution and containing a relatively small amount of metal atoms using a relatively small equivalent numbers of an alkali relative to the hydroxyl groups.

The manufacturing process of cellulose ethers involves a step to etherizing cellulose by adding an etherizing agent (e) to a cellulose solution or dispersion (A) containing an amine (a1) or a quaternary ammonium salt (a2), an ionic liquid (b), water (c) and cellulose (d). (A) contains 1-31 wt.%, relative to the weight of (A), of the amine (a1) or the quaternary ammonium salt (a2), 11-91 wt.% of the ionic liquid (b), 6-65 wt.% of water (c) and 1-20 wt.% of (d).