Nanoparticle technology has played an important role in fabrication of a particulate device for efficient delivery of therapeutic agents. Because of the small dimensions in nano to submicro meter order, nanoparticulate devices are capable of an enhanced penetration and distribution in organs and/or tissues and thus allow direct interaction with cell surfaces, leading to better treatment efficacy. Furthermore, nanoparticles can be utilized as a functional building block for constructing appropriate nano-structures on conventional particulate systems such as tablets and granules. This paper describes our approaches toward fabrication of nanoparticulate systems for biomedical use. These include nanoparticulate carriers for oral delivery of peptide-based drugs and for tumor-specific atom delivery in neutron-capture therapy of cancer, and micro-particulate controlled-release systems assembled from nanoparticulate components. The concepts, the material designs, the particle process technologies, and the properties of such nano-and micro-particulate drug delivery systems are discussed.