In this paper, the desiccant rotor with double ventilation system is proposed in order to improve the sorption efficiency of the rotor. In this system, the processing air is dehumidified with the rotor. Next, the air becomes high relative humidity by cooling with an air cooler, and it is ventilated to the rotor again for dehumidification. This desiccant rotor with the organic sorbent has high adsorption ability at high relative humidity and can be recovered at low temperature. In this study, ventilation experiments of four types of air flow routes were investigated. In the experiment, temperature and absolute humidity of the air at the entrance and exit of each zone were measured. It is clarified that each route has own characteristics on dehumidification. As a result, it is found the most suitable route of the double ventilation dehumidification system.