The micro-plasma emission detector unit is for use with a gas chromatograph. It includes an airtight housing having an internal ionization chamber, a pair of spaced-apart ionization electrodes positioned on opposite sides of the housing, and a set of opposite first and second holding members between which the housing is maintained inside the detector unit. Each electrode is maintained against an outer surface of the housing using a corresponding force-generating mechanism. With the proposed design, the risks of damaging the housing due to the thermal stresses are mitigated and the operating temperature of the detector unit can be increased.