A drive unit for a micro valve comprises a housing, a spring and at least one shape memory alloy element which is attached to the housing in a deflectable manner. The shape memory alloy element is loaded by the spring towards a deflected position and is movable in response to a temperature increase and the shape memory effect activated thereby, into a position which is at least less deflected against an increasing load by the spring. A normally closed micro valve includes a fluid housing, at least one valve seat, a sealing element opposite the valve seat, and a drive unit of the type mentioned above. The shape memory alloy element cooperates with the sealing element and exerts an operating force on the sealing element for closing and opening the valve seat with or against a compression spring force.