Polymeric materials have unique properties, such as flexibility and easy processability via spin-coating, ink-jet printing, and roll-to-roll processing. Thus, polymer-based memory devices have received significant attention because of their many advantages, including low fabrication cost, good scalability, printability, simplicity of device structure, and three-dimensional stackability. Among polymeric materials, random polymers have been predominantly used for the development of several types of polymer-based memory device. This chapter describes non-volatile memory devices based on polymers containing electron-donating and/or accepting groups among various organic materials. Depending on the polymer structure, well-defined homopolymers, rod–coil block copolymers, and coil–coil block copolymers have been categorized, and various memory devices have been fabricated using each polymer; these devices showed biswitching behavior. The different performances of the devices have also been demonstrated using different electrodes and some additives.