The electrical properties of a device with an Al/Alq3/ nanostructured MoO3/Alq3/p+-Si structure were investigated for organic resistance switching memories. The conductance of the device can be electrically switched to either high conductance or low conductance. The bistable switching of the device is attributed to the MoO 3 nanoclusterlike layer interposed between the Alq3 thin films. When the device was switched to high conductance, a space-charge field dominated carrier transportation of the device. The space-charge field was resulted from charges trapped in the MoO3 nanoclusterlike layer. Both retention measurement and write-read-erase-read cycles of the device are also provided.