Cellulose derivative particles including an alkoxy group having 2 or more carbons or an acyl group having 3 or more carbons, wherein the cellulose derivative particles have an average particle size of 80 nm or greater and 100 μm or less, a sphericity of 70% or greater and 100% or less, and a surface smoothness of 80% or greater and 100% or less; and a total substitution degree of the cellulose derivative is 0.7 or greater and 3 or less.