An apparatus for thermoforming plastic containers comprising: at least one thermoforming device suitable for thermoforming a flat sheet for making a container equipped with an upper flange projecting outward; and at least one extracting device associable with the thermoforming device for extracting from the thermoforming device the already thermoformed container equipped with the upper flange; wherein when the extracting device is associated with the thermoforming device for extracting the thermoformed container, the extracting device and the thermoforming device define together a perimetric mould suitable for hot bending and shaping the container's annular flange previously thermoformed by the thermoforming device, before the container is extracted from the thermoforming device; wherein the thermoforming device comprises a shaped mould and a closing element which are movable relative to each other between a home position in which they are at a distance from one another, and a forming position in which they are near each other for, in use, clamping between them the flat sheet of thermoformable plastic material, and one or more heating elements of the closing element and/or of the shaped mould; wherein the extracting device is associable with the shaped mould when the shaped mould and the closing element are in the home position, and wherein the extracting device forms the perimetric mould with the shaped mould. at least one thermoforming device suitable for thermoforming a flat sheet for making a container equipped with an upper flange projecting outward; and at least one extracting device associable with the thermoforming device for extracting from the thermoforming device the already thermoformed container equipped with the upper flange; wherein when the extracting device is associated with the thermoforming device for extracting the thermoformed container, the extracting device and the thermoforming device define together a perimetric mould suitable for hot bending and shaping the container's annular flange previously thermoformed by the thermoforming device, before the container is extracted from the thermoforming device; wherein the thermoforming device comprises a shaped mould and a closing element which are movable relative to each other between a home position in which they are at a distance from one another, and a forming position in which they are near each other for, in use, clamping between them the flat sheet of thermoformable plastic material, and one or more heating elements of the closing element and/or of the shaped mould; wherein the extracting device is associable with the shaped mould when the shaped mould and the closing element are in the home position, and wherein the extracting device forms the perimetric mould with the shaped mould. wherein when the extracting device is associated with the thermoforming device for extracting the thermoformed container, the extracting device and the thermoforming device define together a perimetric mould suitable for hot bending and shaping the container's annular flange previously thermoformed by the thermoforming device, before the container is extracted from the thermoforming device; wherein the thermoforming device comprises a shaped mould and a closing element which are movable relative to each other between a home position in which they are at a distance from one another, and a forming position in which they are near each other for, in use, clamping between them the flat sheet of thermoformable plastic material, and one or more heating elements of the closing element and/or of the shaped mould; wherein the extracting device is associable with the shaped mould when the shaped mould and the closing element are in the home position, and wherein the extracting device forms the perimetric mould with the shaped mould.