The present invention relates to [1] alkali agent-containing particles which are free from deterioration of dissolvability in water and excellent in anti-caking property and which include (a) particles containing an alkali agent and having an average particle size of from 150 to 1000 μm, and a layer of (b) clay mineral particles exhibiting a water impregnation capacity of 200% by mass or more as calculated according to the following method and having an average particle size of from 1 to 200 μm, the layer being formed on a surface of the respective particles (a); and [2] a method for suppressing caking of the alkali agent-containing particles including the step of forming a layer of the clay mineral particles (b) on a surface of the respective particles (a):Method for calculation of water impregnation capacity:A dispersion of the clay mineral particles (b) obtained after measuring a swelling power thereof according to JBAS-104-77 is subjected to suction filtration to measure a mass (A) of a residue of the clay mineral particles (b) on a filter paper; the clay mineral particles (b) are dried according to JIS K0068 “Loss-on-Drying Method” to measure a mass (B) of the dried clay mineral particles (b); and a water impregnation capacity of the particles (b) is calculated from the thus measured mass (A) and mass (B) according to the following formula: Water impregnation capacity (%)=[(A−B)/B]×100.