The mechanism of moisture transfer into shredded tobacco was investigated in connection with moistening process control in cigarette manufacturing. For shredded tobaccos of less than about 1.0 mm shred width, the moisture was sorbed mainly through the cut faces rather than through the leaf epidermis, indicating that the moisture diffusion within the leaf was the rate limiting step of moisture transfer. The moisture diffusion coefficient values within the cured tobacco leaf ranged from 8.80 × 10−7 to 64.2 × 10−7cm2-s−1 depending on the type of tobacco, the shred width of tobacco and the temperature at sorption. But these values were not affected by the relative humidity at sorption. The entire moisture transfer into the shredded tobacco leaves was predictable with the diffusion theory.