To provide an air compressor capable of reducing vibration associated with operation, as compared with conventional ones, while avoiding an increase in a body weight.

A driving shaft 23 is elastically coupled to a crankshaft 32 of a compression mechanism unit 3 so that rotation can be transferred thereto, via a flexible coupling 26 having elasticity or flexibility and serving as a rotation transfer member. A motor 2 is separated from the compression mechanism unit 3 and is fixed to a frame 42a, which connects two air tanks 41 of a tank unit 4, by a fastener 45 (fitting) such as a bolt. The compression mechanism unit 3 is elastically coupled to a frame 42b, which connects the two air tanks 41 of the tank unit 4, via an elastic member 43 by a fastener 44 (fitting) such as a bolt.