Machine tool comprising a system for fastening workpieces to be machined, said system comprising: a support, which is substantially flat, for supporting at least one workpiece to be machined, at least one opening (9, 23) being formed in said support; a depression generation system which is connected with said at least one opening (9, 23) for generating a depression in said at least one opening (9, 23); and at least one closure member (10, 20) which is placed at said at least one opening (9, 23), said at least one closure member (10, 20) comprising a valve element (12, 26) bearing a magnetic field-sensitive element (14, 27), said valve element (12, 26) being movable between a closing position, where said valve element (12, 26) covers said at least one opening (9, 23) while preventing said depression from reaching, in use, said at least one workpiece to be machined placed above said support, and an opening position, where said at least one opening (9, 23) is kept at least partially open by said valve element (12, 26) while allowing said depression to fasten, in use, said at least one workpiece to be machined to said support, such that said valve element (12, 26) is able to move from said closing position to said opening position or from said opening position to said closing position by applying, when in use, at a distance, a magnetic force to said magnetic field-sensitive element (14, 27); wherein said machine tool further comprises an operative head, which is movable, for machining workpieces, and a control member for controlling said at least one closure member (10, 20), characterised in that said control member is configured to be mounted to said operative head and comprises a magnetic element capable of generating a magnetic force to interact, at a distance, with said magnetic field-sensitive element (14, 27) of said at least one closure member (10, 20). a support, which is substantially flat, for supporting at least one workpiece to be machined, at least one opening (9, 23) being formed in said support; a depression generation system which is connected with said at least one opening (9, 23) for generating a depression in said at least one opening (9, 23); and at least one closure member (10, 20) which is placed at said at least one opening (9, 23), said at least one closure member (10, 20) comprising a valve element (12, 26) bearing a magnetic field-sensitive element (14, 27), said valve element (12, 26) being movable between a closing position, where said valve element (12, 26) covers said at least one opening (9, 23) while preventing said depression from reaching, in use, said at least one workpiece to be machined placed above said support, and an opening position, where said at least one opening (9, 23) is kept at least partially open by said valve element (12, 26) while allowing said depression to fasten, in use, said at least one workpiece to be machined to said support, such that said valve element (12, 26) is able to move from said closing position to said opening position or from said opening position to said closing position by applying, when in use, at a distance, a magnetic force to said magnetic field-sensitive element (14, 27); wherein said machine tool further comprises an operative head, which is movable, for machining workpieces, and a control member for controlling said at least one closure member (10, 20), characterised in that said control member is configured to be mounted to said operative head and comprises a magnetic element capable of generating a magnetic force to interact, at a distance, with said magnetic field-sensitive element (14, 27) of said at least one closure member (10, 20).