A single-arm micro air-pressure pump device, having an air pump body and a driving unit. The air pump body includes a supporting frame, an air chamber unit coupled to a side of the supporting frame, and a swing arm provided on the air chamber unit. The driving unit is fixed on the supporting frame and has an output shaft. The output shaft is provided with an eccentric shaft and is configured to rotate the eccentric shaft, and the eccentric shaft has an end coupled to the output shaft and an opposite end coupled to the swing arm in order to drive the swing arm into a reciprocating motion between at least a proximal position and a distal position with respect to the air chamber unit. The reciprocating motion pushes a piston unit provided on one end of the swing arm and causes the air output.
