PROBLEM TO BE SOLVED: To obtain a soil improving fertilizer capable of exhibiting an effectiveness sustainedly in a poor soil, and accelerating the organizing action of the soil. SOLUTION: This soil improving fertilizer contains mineral components such as nitrogen, phosphoric acid, potassium, etc., in a copolymer of acrylamide, potassium acrylate, etc. The fertilizer makes a soil rich in aggregated particles 4, and exhibits both immediate and delayed effects. Further, it accelerates the propagation of microorganisms and the organizing action of the soil by impregnated with organic substances