To obtain a magnet manure for horticulture, capable of promoting the growth of a plant by magnetic energy of magnets, hardly polluting environment by finally returning to soil, and capable of recycling a raw material by regenerating the raw material.

This magnetic manure 1 for horticulture is obtained by heating and softening a mixture obtained by mixing a synthetic resin material degraded by microorganisms, that is a biodegradable plastic 3, with magnetic powder in a suitable amount, forming the obtained mixture to provide a product having a largeness suitable for scattering on a soil by methods such as the method for forming the obtained mixture into a long string-like shape by using an extruder and cutting the string-like product at several mm length to form a lump shape, the method for molding the obtained mixture into a lump shape or a granular shape by using an injection molding machine and the method for forming into the granular shape by using a Henschel mixer or the like, and magnetizing the formed product.