A support for a lithographic printing plate having a corrugated surface processed by roughening, wherein the corrugation on the support surface comprises big corrugation having an average pitch of from not less than 5 .mu.m to not more than 30 .mu.m, and middle corrugation superimposed on the big corrugation, the middle corrugation comprising honeycomb pits having an average diameter of from not less than 0.5 to not more than 3.0 .mu.m, and the support surface has a surface inclination distribution which comprises an inclination of not less than 30 degrees in a proportion of from not less than 5% to not more than 20% as determined by an atomic force microscope. A process for the preparation of the support and an electrolytic treatment apparatus for the process are also described.