The present disclosure relates to a device for applying inserts on skins, fabrics, clothes, or similar products. The device includes a first support having a constraining portion configured for being stably engaged to a bed of a press and a housing portion having a plurality of seats. The device also includes a second support having a respective auxiliary constraining portion configured for engaging a movable element of the press and an auxiliary housing portion having a predetermined number of auxiliary seats. The device also includes retaining elements, each having an external outline configured for being housed in a respective seat of the housing portion of the first support and a respective receiving seat for removably receiving an insert to be applied to a sheet support. A predetermined number of constraining elements are associable to the auxiliary seats and are configured for being constrained to the insert in use.