The microdrive is one of the most essential tools for extracellular, single-unit recordings in freely behaving animals to detect and isolate the single-unit activities from brain regions of interest. Due to the increasing number of neuroscience research projects using genetically engineered mice, the demand for effective recording devices in freely moving mice is also increasing. Although manually and automatically operated microdrive devices are available, they are limited in terms of size, weight, accuracy, manipulability, and convenience for single-unit recording in mice. The present study proposed a novel microdrive that employs a small, lightweight piezo-motor and a magnetoresistive (MR) sensor with a closed-loop position feedback control system.