Acid-type carboxylated cellulose nanofibers

The present invention addresses the problem of providing acid-type carboxylated cellulose nanofibers having a high viscosity in a low shear region, or acid-type carboxylated cellulose nanofibers having extremely short fiber lengths. The carboxylated cellulose nanofibers have a carboxyl group on at least a portion of structural units constituting a cellulose molecule chain, wherein: the viscosity of an aqueous dispersion in which the content rate of the acid-type carboxylated cellulose nanofibers is 0.95-1.05 mass%, is 400 Pa·s or higher at 30oC and a shear rate of 0.003-0.01 s -1 ; or the average fiber length of the acid-type carboxylated cellulose nanofibers is 50-500 nm, and the proportion of the fibers each having a fiber length of 300 nm or less is 50% or more.