This invention relates to a dewatering device for dewatering a material web (5), particularly a tissue web, in a paper machine where the dewatering device is placed after a forming unit (16) and before a thermal drying device (11). The dewatering device consists of a press roll (1) with a press belt (3) running round it. Here, the material web (5) is carried into the dewatering device either on a water-absorbing belt (4) or on a wire (10). The water-absorbing belt (4) is placed in the dewatering device between the material web (5) and the press belt (3). This invention also relates to a dewatering process performed with the dewatering device.