DECIGO Pathfinder (DPF) is the first precursory satellite mission for DECIGO (DECi-hertz Interferometer Gravitational wave Observatory), which is a future space gravitational wave antenna. The key instrument of DPF is a Fabry-Perot laser interferometer with freely floating test-masses, demonstrating precision laser interferometry, stabilized laser system and drag-free control system in orbit. A test-mass module is one of the sub-components of the DPF instrument, realizing non-contact suspension of the test mass in space, which provides capabilities of local sensing/actuation, test-mass lock mechanism and charge management system. In this article, the test-mass module system is reviewed.