While millimeter-wave (mm-wave) communication can provide abundant spectrum and support high data rate for future 5G systems, its coverage capability in urban environments is a critical issue due to the severe penetration loss. In this letter, we propose a simple scheme to enhance the coverage area of a cell centered with an mm-wave base station. This key idea is to employ multiple passive-reflectors to reflect the mm-wave to the non-lineof-sight (NLOS) regions with low received power levels. In order to improve the received power, a design method for the passivereflector is discussed intensively. Numerical experiment for an outdoor urban environment is presented. The numerical results show that, with the proposed scheme, the coverage radius of an mm-wave cell can be remarkably increased. This indicates that our scheme is an attractive option to alleviate the mm-wave coverage problem for future 5G systems.