A machine for making filter bags for infusion products, each filter bag being obtained from a piece of filter material to which a thread is tied for connection with a gripping tag; the machine for making filter bags comprising at least: - a wheel defining a work surface; the wheel being rotary about its own axis in such a way to define a working path having a circular feed direction; - a first feed station adapted to feed individual tags, in phase, on the work surface in a predetermined depositing zone of the working path; - a second feed station adapted to feed the continuous thread on the work surface along a weave path, starting from a predetermined zone downstream of the zone for depositing the individual tags with reference to the feed direction of the wheel; - a third feed station adapted to feed a continuous strip of filter material on the work surface superposing the weave of thread and the tag positioned downstream relative to the second feed station with reference to the feed direction of the wheel; - sealing means (8, 9), positioned downstream of the first and second feed station with reference to the feed direction of the wheel, adapted to make seals between the thread, the tag and the strip of filter material; - at least a first feed device adapted to move the strip of filter material along a feed line and located downstream of the operating wheel with reference to the feed direction of the strip of filter material; - a forming station for completing the filter bag equipped with the tag and the thread, positioned downstream of the feed device with reference to the feed direction of the strip of filter material, and adapted to form the filter bag, to introduce a dose of infusion product in the filter bag formed and to close the filter bag containing the dose of infusion product, wherein the first feed device comprises two first feed rollers (12, 13) for unwinding in a controlled, variable manner, the quantity of strip of filter material to be placed on the work surface of the wheel, characterized in that said two first feed rollers (12, 13) are controlled by a control system for adjusting, by means of a motor, the speed of rotation of the two first feed rollers (12, 13) as a function of the length of the piece of filter material needed to form a filter bag of desired size, and in that the machine comprises a device for transferring the strip of filter material to move transversely the strip of filter material being fed, adapted to modify the position of a centre-line axis of the strip of filter material in such a way that the centre-line axis of the strip of filter material coincides with a working line on the work surface of the wheel; said working line being parallel to the line for feeding the strip of filter material and defined as a function of the size of the desired filter bag. - a wheel defining a work surface; the wheel being rotary about its own axis in such a way to define a working path having a circular feed direction; - a first feed station adapted to feed individual tags, in phase, on the work surface in a predetermined depositing zone of the working path; - a second feed station adapted to feed the continuous thread on the work surface along a weave path, starting from a predetermined zone downstream of the zone for depositing the individual tags with reference to the feed direction of the wheel; - a third feed station adapted to feed a continuous strip of filter material on the work surface superposing the weave of thread and the tag positioned downstream relative to the second feed station with reference to the feed direction of the wheel; - sealing means (8, 9), positioned downstream of the first and second feed station with reference to the feed direction of the wheel, adapted to make seals between the thread, the tag and the strip of filter material; - at least a first feed device adapted to move the strip of filter material along a feed line and located downstream of the operating wheel with reference to the feed direction of the strip of filter material; - a forming station for completing the filter bag equipped with the tag and the thread, positioned downstream of the feed device with reference to the feed direction of the strip of filter material, and adapted to form the filter bag, to introduce a dose of infusion product in the filter bag formed and to close the filter bag containing the dose of infusion product, wherein the first feed device comprises two first feed rollers (12, 13) for unwinding in a controlled, variable manner, the quantity of strip of filter material to be placed on the work surface of the wheel, characterized in that said two first feed rollers (12, 13) are controlled by a control system for adjusting, by means of a motor, the speed of rotation of the two first feed rollers (12, 13) as a function of the length of the piece of filter material needed to form a filter bag of desired size, and in that the machine comprises a device for transferring the strip of filter material to move transversely the strip of filter material being fed, adapted to modify the position of a centre-line axis of the strip of filter material in such a way that the centre-line axis of the strip of filter material coincides with a working line on the work surface of the wheel; said working line being parallel to the line for feeding the strip of filter material and defined as a function of the size of the desired filter bag.