A method of producing an agricultural product for improving immunity, the agriculture product being rice, includes: (1) soaking seeds of the agricultural product in a solution containing a magnetic material and a β-glucan； (2) before planting the seeds, applying a bottom fertilizer to a paddy field for the agricultural product, the bottom fertilizer including an organic fertilizer, the magnetic material, an oyster shell powder, the (3-glucan and an organic zinc； and (3) at tillering stage, applying a topdressing to the paddy filed, the topdressing including the β-glucan and the organic zinc.
