The effect of the pretreatment of ultrasonic irradiation on the deliquoring properties in expression was investigated by using carrots as an example of vegetables. The results indicated that the ultrasonic pretreatment produced a noticeable improvement in deliquoring behaviors such as the deliquoring rate and cake moisture content due to the physical damage of cell tissue, although the carrots were maintained in the original shape before and after ultrasonic irradiation. The time variation of the cake moisture content during the course of expression was well described by the three-stage creep model combined with the modified Terzaghi model. It was necessary to heat carrots above 50 degrees C during ultrasonic irradiation in order to attain a desired effect in expression since carrots lost cell turgor pressure rapidly through beta-elimination reaction occurring at about 50 degrees C. The ultrasonic pretreatment was well evaluated from the viewpoint of the ultrasonic energy dissipated in the sample. The cake moisture content after 24 h from the beginning of expression dramatically decreased from 69 to 47% by increasing the pressure from 0.5 to 10 MPa, indicating that the cake consisting of treated carrots behaved as the compressible material in the expression operation.