To provide a manufacturing method of magnetically active deep player water constituted so as to effectively utilize one layer of palatable deep water rich in nutrient salts or minerals.

In this manufacturing method of magnetically active deep water, deep water or salt-reduced/desalted deep water is treated magnetically. Alternatively, the magnetic treatment of deep water is performed by passing deep water through the magnetic field with a magnetic flux density of 5,000-50,000 gauss between permanent magnets.