A ruler band guide (1, 1') for the lateral guidance of a metal sheet capable of being cut on a cold cutting matrix, the sheet travelling over said matrix, which is flat, said sheet being subsequently capable of being transformed at a hot or cold stamping station, one or more ruler band guides (1, 1') being fixedly or movably disposed on the cutting matrix, wherein the ruler band guide (1, 1') comprises: - a body (20, 20') featuring at least one longitudinal orifice, and - a roller assembly, which is installable within the longitudinal orifice, and characterised in that: - the body (20, 20') is formed by a lower portion (2, 2') and a projecting upper portion (3, 3'), disposed transversally with regard to the lower portion (2, 2'), thus forming an inverted L-shaped configuration, - the roller assembly comprises: - a rotating drum featuring an external cylindrical surface and with an internal orifice, - respective bearings (10, 12) on either side of the rotating drum, - a supporting washer disposed at the lowest point of the roller assembly, and - a drum shaft disposed through the interior of the internal orifice of the rotating drum, wherein the drum shaft presents a broadened upper portion and a lower portion in the form of a shaft (9b, 9c, 9d), and - the lower portion of the body presents an opening at the frontal side in order that part of the drum may protrude through said opening, in such a way that the contact between the external surface of the drum and a lateral base of the sheet is point contact or almost point contact, reducing to a minimum the friction between both items (ruler guide - sheet); and - the at least one longitudinal orifice is extended superiorly so forming a broadened part with a diameter greater than that of the remainder of the central orifice, wherein said broadened part presents an external outline equal to the outline of said broadened portion of the drum shaft, to ensure the perfect seating of the lower base of the broadened portion of the drum shaft on said broadened part. - a body (20, 20') featuring at least one longitudinal orifice, and - a roller assembly, which is installable within the longitudinal orifice, and characterised in that: - the body (20, 20') is formed by a lower portion (2, 2') and a projecting upper portion (3, 3'), disposed transversally with regard to the lower portion (2, 2'), thus forming an inverted L-shaped configuration, - the roller assembly comprises: - a rotating drum featuring an external cylindrical surface and with an internal orifice, - respective bearings (10, 12) on either side of the rotating drum, - a supporting washer disposed at the lowest point of the roller assembly, and - a drum shaft disposed through the interior of the internal orifice of the rotating drum, wherein the drum shaft presents a broadened upper portion and a lower portion in the form of a shaft (9b, 9c, 9d), and - the lower portion of the body presents an opening at the frontal side in order that part of the drum may protrude through said opening, in such a way that the contact between the external surface of the drum and a lateral base of the sheet is point contact or almost point contact, reducing to a minimum the friction between both items (ruler guide - sheet); and - the at least one longitudinal orifice is extended superiorly so forming a broadened part with a diameter greater than that of the remainder of the central orifice, wherein said broadened part presents an external outline equal to the outline of said broadened portion of the drum shaft, to ensure the perfect seating of the lower base of the broadened portion of the drum shaft on said broadened part. - the body (20, 20') is formed by a lower portion (2, 2') and a projecting upper portion (3, 3'), disposed transversally with regard to the lower portion (2, 2'), thus forming an inverted L-shaped configuration, - the roller assembly comprises: - a rotating drum featuring an external cylindrical surface and with an internal orifice, - respective bearings (10, 12) on either side of the rotating drum, - a supporting washer disposed at the lowest point of the roller assembly, and - a drum shaft disposed through the interior of the internal orifice of the rotating drum, wherein the drum shaft presents a broadened upper portion and a lower portion in the form of a shaft (9b, 9c, 9d), and - a rotating drum featuring an external cylindrical surface and with an internal orifice, - respective bearings (10, 12) on either side of the rotating drum, - a supporting washer disposed at the lowest point of the roller assembly, and - a drum shaft disposed through the interior of the internal orifice of the rotating drum, wherein the drum shaft presents a broadened upper portion and a lower portion in the form of a shaft (9b, 9c, 9d), and - the lower portion of the body presents an opening at the frontal side in order that part of the drum may protrude through said opening, in such a way that the contact between the external surface of the drum and a lateral base of the sheet is point contact or almost point contact, reducing to a minimum the friction between both items (ruler guide - sheet); and - the at least one longitudinal orifice is extended superiorly so forming a broadened part with a diameter greater than that of the remainder of the central orifice, wherein said broadened part presents an external outline equal to the outline of said broadened portion of the drum shaft, to ensure the perfect seating of the lower base of the broadened portion of the drum shaft on said broadened part.