To provide a dehumidifying method and device in which the dehumidified quantity is increased by using the same power and also the device structure is simplified.

This dehumidifying method contains a dehumidifying process wherein air to be dehumidified is passed through one area of a rotary hygroscopic member having plural through-holes having hygroscopic material which can reversely absorb moisture in the air at least on the inner surface thereof, a process wherein the air from which moisture has been removed is discharged to outside the device, a process wherein regenerating air heated by a heater is passed through the other area of the hygroscopic member to regenerate the hygroscopic member, and a process wherein the regenerating air form which bedewed water has been removed is heated by the heater and is circulated into the process wherein the hygroscopic member is regenerated. The regenerating air and the air to be dehumidified are not substantially mixed, and heat exchange is performed between the regenerating air after the hygroscopic member regeneration and the air to be dehumidified before being introduced into the hygroscopic member to perform the process wherein the regenerating air is cooled and bedewed, and the regenerating air does not perform heat exchange except this heat exchange.