The disclosure relates to an apparatus for conveying and folding flexible packaging material, comprising a conveyor (1) with a conveyor belt (3) which is provided with through-going holes and which, for a part of its length, extends substantially rectilinearly and with constant orientation along a suction box (9). By connecting the suction box (9) to a source of partial vacuum, a partial vacuum is created at the side of the belt facing towards the packaging material, which ensures that the packaging material is well-fixed and can thereby pass closely adjacent and be heated by a heating device (15) extending along the belt. The apparatus makes for concentrated, energy-efficient and well-defined heating of an edge region of the packaging material intended for thermosealing.