Abstract: The invention relates to an electric compressor (1) comprising a compression mechanism (3) rotated by a drive device that extends through a main casing (5) defining an internal volume (6) in which an electric motor (2) is installed. The electric motor comprises a stator (10) and a rotor (11) which extends at least partially on the outer periphery of the stator (10), said drive device comprising the rotor (11) solidly connected to a shaft (4) which extends through a plate (7) solidly connected to the main casing (2). The invention is characterised in that it includes a first rotation means (47) between the shaft (4) and the plate (7) and a second rotation means (51) between the drive device and the plate (7). The invention is suitable for motor vehicles.