PROBLEM TO BE SOLVED: To provide a heating method and device capable of maintaining a heating environment, for example, when agricultural products are grown in a planting space such as a plastic greenhouse or when fish and shellfish are cultured in a water tank, by effectively using propylene glycol as a heating medium which is extremely harmless to a human body and has high specific heat.SOLUTION: The heating method comprises: circulating a heat medium in a circulation pipe, the heat medium comprising water, 20 to 40 wt.% of propylene glycol and glycerin by &le；7% with respect to the propylene glycol； and heating a material to be heated selected from one of soil, water and air which is in contact with the circulation pipe.
