An apparatus for thermoforming plastic containers comprising: a pickup station; a feeder for feeding flat sheets of thermoformable plastic material to the pickup station; a thermoforming device in turn comprising a shaped mould and a closing element, the shaped mould and the closing element being movable relative to each other at least between a home position in which they are away from one another, and a forming position in which they are near to each other for, in use, clamping a flat sheet between them; the closing element comprising a resting surface that is facing the shaped mould at least when they are in the forming position, and being equipped with suction means designed to retain on the resting surface at least one of said flat sheets at least when the shaped mould and the closing element are in the home position; one or more heating elements for heating the closing element; a transferring device for transferring the flat sheets from the pickup station to the closing element; an extracting device for extracting the thermoformed container from the shaped mould; and an electronic unit for controlling and checking operation of the apparatus; characterised in that: it comprises a plurality of said thermoforming devices, each in turn comprising a shaped mould and a closing element, the shaped moulds and the closing elements of said plurality of thermoforming devices being simultaneously movable at least between the corresponding home and forming positions, and the closing elements of said plurality of thermoforming devices having fixed first mutual positions at least when they are in the home position; the pickup station comprises a positioning device for, in use, positioning a plurality of flat sheets arriving from the feeder, in a plurality of pickup locations mutually arranged with second mutual positions, the number of pickup locations being equal to the number of thermoforming devices; and the transferring device is designed to simultaneously transfer a plurality of flat sheets positioned in the pickup locations to the closing elements. a pickup station; a feeder for feeding flat sheets of thermoformable plastic material to the pickup station; a thermoforming device in turn comprising a shaped mould and a closing element, the shaped mould and the closing element being movable relative to each other at least between a home position in which they are away from one another, and a forming position in which they are near to each other for, in use, clamping a flat sheet between them; the closing element comprising a resting surface that is facing the shaped mould at least when they are in the forming position, and being equipped with suction means designed to retain on the resting surface at least one of said flat sheets at least when the shaped mould and the closing element are in the home position; one or more heating elements for heating the closing element; a transferring device for transferring the flat sheets from the pickup station to the closing element; an extracting device for extracting the thermoformed container from the shaped mould; and an electronic unit for controlling and checking operation of the apparatus; it comprises a plurality of said thermoforming devices, each in turn comprising a shaped mould and a closing element, the shaped moulds and the closing elements of said plurality of thermoforming devices being simultaneously movable at least between the corresponding home and forming positions, and the closing elements of said plurality of thermoforming devices having fixed first mutual positions at least when they are in the home position; the pickup station comprises a positioning device for, in use, positioning a plurality of flat sheets arriving from the feeder, in a plurality of pickup locations mutually arranged with second mutual positions, the number of pickup locations being equal to the number of thermoforming devices; and the transferring device is designed to simultaneously transfer a plurality of flat sheets positioned in the pickup locations to the closing elements.