A sustained-release solid pesticidal formulation comprising pesticidal active ingredient and a zeolite as specified below, wherein the solubility in water of the pesticidally active ingredient is 100 to 100000 mg/L, and wherein the zeolite has SiO2 and Al2O3 in total of 90% by weight or more to the weight of the zeolite, has molar ratio of SiO2/Al2O3 of 4 or more, and has an average particle size of 10 μm or less.