To provide a book forming and pressing machine which is operated for a straight book block back and in which a mutual interval between prism plates can be minimized.

A book forming and pressing machine is comprised of a reshaping device, a pressing device 30, a loading device 60, and a loading table 62. The pressing device 30 is comprised of a plurality of press plates 31 and 32 whose mutual interval is adjustable and burn-in rails 35 and 36. The loading table 62 has a support means which satisfies a support function for a book block back and is operatively connected with a shaping part thereof. The support means is comprised of at least a pair of prism plates 66 and 67 which extends in parallel, leaving an interval therebetween. The prism plates 66 and 67 each include at least one operativebly connected position-switchable adjusting element 71. The adjusting element 71 is so formed as to bear a function complying with the prism plates 66 and 67 for another shaping of the book block back.