A squeezing device capable of squeezing a viscous liquid in a packaging bag includes a pair of bag body support parts for stretching and supporting the bag bodies by fixing the front end and the rear end of a bag body and performing fixing of the rear end by applying a tension thereto rearwards; a squeezing mechanism part which is so provided as to be capable of sliding in the direction towards the front end in such a state the rear end of the bag supported by the bag body support parts is held from the upper and lower sides; and a drive mechanism part for slidingly driving the squeezing mechanism part in the direction towards the front end. The squeezing mechanism part is installed at the tip end of the device, and the drive mechanism part includes a slide bar disposed parallel to the sliding direction of the squeezing mechanism part.