In a warp let-ff control method performed by a let-off device of a loom, the loom used for weaving a fabric (2a) having two or more weave sections with different densities, the loom including the let-off device that controls an amount of warp let-off by performing let-off control in which a let-off motor (5c) is driven in accordance with a detected tension and a target tension, and a temple device (40) including a temple (41) that is displaceable between an operating position and a standby position, the temple device automatically switching a position of the temple between the two positions in accordance with a weft density of one of the weave sections to be woven, the method includes controlling driving of a let-off motor with a control mode during a control period including a period during which the temple is displaced, the control mode adjusting an amount of warp let-off in a direction such that a change in a warp tension due to the displacement of the temple is cancelled out, the control mode being different from a control mode for performing let-off control in a normal operation of the loom after the control period.