Some kinds of bioceramics have been disclosed to be converted by electric polarization to electrets; above all, the electrets of hydroxyapatite (HAp), with the best biocompatibility, exhibit the excellence in the biological and biomedical effects as well as chemical and physical ones [1–5]: The studies in vivo have demonstrated the effectiveness on reconstruction of bones and teeth in orthopedic and dental clinical applications [2–5], and on regeneration of nerves [6] and blood vessels [7]. The phenomena of acceleration and deceleration in the growth of bone like crystals were observed on negatively charged and positively charged surfaces in simulated body fluid, respectively [1]. Our recent studies have demonstrated high quasi-permanent surface potentials with symmetry on both sides of flat HAp electrets. In addition to HAp, Sr-HAp [8] and carbonate apatites [9], the bioceramic electrets have been successfully prepared to date through electrical polarization of ß-calcium phosphates [10], 45S5-type bioglasses [11] and the mixed glasses of 45S5-calcium aluminophosphosilicates [12], titania and zirconia ceramics [13]. These bioceramic electrets are defined as vector materials for biointerfacial engineering [14], and a further concept of vector materials science will be introduced. We will show the fundamental and biomedical properties of vector materials.