A porous honeycomb structure includes: a plurality of partition walls containing cordierite as a main component and constituted of a porous ceramic having a porosity of 55 to 75% and an average pore diameter of 15 to 35 \u03bcm, wherein the partition walls have a pore distribution represented by the following condition formula :Lr>0. In a positive photoresist containing an alkali-soluble novolak resin and a quinone diazide compound, the film thickness of the photoresist at the time of exposure is not larger than 100 nm, and the absorption coefficient of the photoresist \u03b1 for the exposure light is such that 0. After the failing facility is repaired, the film processing controller is restarted to operate the film producing and packaging system, which then automatically discharges a length of the elongate film corresponding to a preset number of sized films. A damping mechanism is clamped between the piston and the wall and an output member linked to the hub.