This chapter reviews MEMS (microelectromechanical systems)-based drug delivery devices with an emphasis on magnetic materials. First, an overview of various types of MEMS drug delivery systems is presented, followed by a focus on MEMS drug delivery devices incorporating magnetic micro/nanoparticle. Each device is discussed according to its capabilities and features. Subsequently, we present one of the most recent on-demand drug delivery devices based on a magnetic sponge, made of porous polydimethylsiloxane (PDMS) mixed with carbonyl iron (CI) magnetic microparticles. The drug is filled in the sponge pores and the sponge can be deformed under an external magnetic field, which then leads to drug release. The final device has a diameter of 6 mm with a thickness of less than 2 mm. Controlled release of methylene blue (MB) and docetaxel (DTX) have been investigated to demonstrate the consistency and flexibility of drug release rates.