The present invention relates to a low-carbon, low-cost agricultural heat-retaining apparatus using the frictional heat of water. The agricultural heat-retaining apparatus according to the present invention comprises: a housing in which an inlet, through which water flows in, and an outlet, through which water is discharged, are defined; a rotating drum which is rotatably installed inside the housing, which is formed so as to have a cylindrical shape and one open end, and in which a plurality of first orifice holes, which are formed so as to be skewed in the direction opposite that in which the rotating drum rotates, are defined; a cylindrical fixed drum which is fixedly installed a certain distance apart from the inside or outside of the rotating drum, and in which a plurality of second orifice holes, which are formed so as to be skewed in the same direction as that in which the rotating drum rotates, are defined; a drive motor for rotating the rotating drum with respect to the housing; a spindle for transmitting the power from the drive motor to the rotating drum; a water impeller, which is installed on the outer periphery of the spindle, for forcibly feeding water from the outside of the inlet to the inside of the inlet; and a guide member, which is installed within the inlet, for guiding the water fed by means of the water impeller toward the center of the rotating drum.
