The aim of this research is to realize a small continuous flow system withemulsification devices. This system is for the generation of sub-micron or nanosize monodisperse emulsions. We have fabricated and evaluated a device whichconsists of a microchannel plate and an ultrasonic vibrating plate. Theoscillating frequency was 2.25 MHz. We have succeeded in generating emulsionswhich have a diameter of 200 nm. This device can realize continuous flow systemand those plates are easily stacked. We also designed the cross-sectionalpattern of microchannel of ultrasonic device to increase the residence timeeffectively. As a result, we have succeeded in obtaining emulsions which have adiameter of 80 nm.