A leather obtained by a (1) pre-treatment before tanning, (2) tanning process where glutaraldehyde is used as a tanning agent, (3) process where a re-tanning agent is used which is constituted by synthetic tannin, resin and aluminum, of which the synthetic tannin is constituted by (a) condensation product of aromatic sulfonic acid with formaldehyde or mixture of aromatic sulfonic acid and condensation product of aromatic sulfonic acid with formaldehyde, (b) methylene cyclic polymer of aromatic sulfonic acid with hydroxy aromatic compound or mixture of aromatic sulfonic acid and methylene cyclic polymer of aromatic sulfonic acid with hydroxy aromatic compound and (c) glyoxal, while the resin is constituted by (a) acrylic acid, methacrylic acid, acrylic acid ester or methacrylic acid ester polymer(s) and mixture thereof, and copolymer(s) thereof or mixture thereof and (b) polycondensation product of melamine with formaldehyde, wherein the re-tanning agent having the aforementioned composition is used to perform re-tanning, followed by dyeing as well as fatliquoring treatment using a fatliquoring agent constituted by (a) synthetic oil and natural oil and (b) mixture of synthetic oil and natural constituent, and (4) post-treatment after re-tanning; wherein said leather is characterized in that it is flexible and has unique elasticity and softness beyond what is presented by the material hide and has restorability that prevents the leather from stretching more than it should, and also in that its conditions include a BLC stiffness/softness of 4.42 mm or more but 4.90 mm or less and maximum set ratio of 10.7 or more but 13.9 or less.