The invention provides an electro-mechanical brake system which can keep a stop state even if a malfunction is generated in a parking brake, and an electro-mechanical brake apparatus used for the electro-mechanical brake system. In accordance with an embodiment, a motor controller may be maintained by tracking a total proportion of power module life expended by a power module in a variable frequency motor controller based on a minimum junction temperature or a mean junction temperature and a junction temperature change, and indicating when the power module is estimated to fail. The OFSCs have colony formation ability and multi-lineage differentiation ability.