To provide a filling and packaging machine capable of compensating shortage of calorie when implementing a heat seal while pressurizing with a longitudinal sealing mechanism without reducing the packaging speed.

In the longitudinal filling and packaging machine, a film folding-back mechanism 14 comprises an inner surface guide member 19 to guide a film F to an inner surface side of the film F which is folded back to two along the width direction of the film F, a pair of right and left preheating block members 21 having an inclined receiving surface 22 or an arc-shaped receiving surface 33 on an outer surface side of the film F via a predetermined interval from the inner surface guide member 19 along the width direction of the film F so that the interval on the upstream side in the carrying direction of the film F is larger than the interval on the downstream side thereof, and a heater H provided inside the preheating block members 21.