The present invention relates to an instantaneous mixing device for injection/extraction cleaning machines and in particular to an instantaneous mixing device with a pre-spray functionality of the type equipped with at least one washing accessory (13) and/or at least one pre-washing accessory (30) connected at the outlet to a hydraulic circuit (20), the device (10) comprising: at least one spray pump (12) connected to the hydraulic circuit (20); at least one tank for water (15) and at least one tank for a chemical product (16), connected to the hydraulic circuit (20); at least one mixing element (14) with a Venturi effect connected downstream of the at least one water tank (15) and at least one tank for a chemical product (16). The at least one pre-washing element (30) preferably comprises a spray hole having greater dimensions with respect to the hole of the spray nozzle of the at least one washing accessory (13).