The invention relates to an electronic control device for an asynchronous, single-phase or three-phase motor, comprising an electronic board (2) and a relay (3) for controlling the power supply to the motor. The aforementioned electronic board (2) comprises at least one microcontroller (7) which analyses the electric parameters of the electric network, such as frequency and voltage, in order to ensure that said parameters are compatible with the correct operation of the motor and to control the relay (3) which is positioned on the motor power supply network. The board (2) and relay (3) are preferably housed inside a casing (1). The inventive device is characterised in that the relay (3) is a static relay and in that the electronic board (2) also comprises: a capacitive impedance (4) which is powered from the motor power supply network and which is used to lower the supply voltage for the rest of the device and at least one commutation element (5) which is used to start and/or stop the device and which can be controlled via a control element (6) which is in turn controlled by a preferably-manual displacement control. The invention can be used to control single-phase or three-phase motors.