The present invention relates to an anti-abandonment system comprising: a first sensor (2) associable with a restraining device (R) placed in the vehicle, a second sensor (3) associable with a fastening tab or with a fastening buckle of a safety belt of the vehicle. The anti-abandonment system comprises a control unit connected to the first and second sensors and configured to perform a control procedure comprising the steps of: determining, as a function of the signal emitted by the first sensor, the presence of a child and/or an infant on the restraining device; determining, as a function of the signal emitted by the second sensor, a fastened or unfastened condition of the safety belt, defining an alarm condition in the event that the control unit determines the presence of a child and/or an infant on the restraining device and at the same time the unfastened condition of the safety belt. The present invention also regards a process for warning of a potentially hazardous situation relative to the presence of an infant/child inside a vehicle.