An outer column (11a-11d), the outer column (11a-11d) formed using a metal material into a cylindrical shape as a whole, and constructing a steering column by fitting with an inner column so that sliding is possible, and comprising: a slit (19a-19d) formed in one half section in an axial direction of the outer column (11a-11d) for decreasing a rigidity in a radial direction of the one half section in the axial direction; and a pair of supported sections (20a, 20b) provided in positions on both sides of the slit (19a-19d) in the width direction of the outer column (11a-11d), with through holes formed in portions thereof that are aligned with each other; the slit (19a-19d) comprising: a main slit section (36, 36a-36c) formed in the axial direction and having a front end section in the axial direction and a rear end section in the axial direction; and a sub slit section formed in a circumferential direction of the front-end section in the axial direction of the main slit section (36, 36a-36c) in case that the outer column (11a-11d) is arranged on a rear side, or in a circumferential direction of the rear-end section in the axial direction of the main slit section (36, 36a-36c) in case that the outer column (11a-11d) is arranged on a front side, with the front or rear end section in the axial direction of the main slit section (36, 36a-36c) being open to a part in the circumferential direction of the sub slit section; characterized in that a length in the circumferential direction from the main slit section (36, 36a-36c) to one end section of both end sections of the sub slit section, which is in one half section in the width direction of the outer column (11a-11d) is longer than a length in the circumferential direction from the main slit section (36, 36a-36c) to the other end section which is in the other half section in the width direction of the outer column (11a-11d); a range where the slit (19a - 19d) is formed in the one half section in the width direction is larger than a range where the slit (19a - 19d) is formed in the other half section in the width direction, and the rigidity in the width direction of the one half section in width direction of the portion where the slit ( 19a - 19d) is formed is less than the rigidity in the width direction of the other half section in the width direction of the portion where the slit (19a - 19d) is formed. a slit (19a-19d) formed in one half section in an axial direction of the outer column (11a-11d) for decreasing a rigidity in a radial direction of the one half section in the axial direction; and a pair of supported sections (20a, 20b) provided in positions on both sides of the slit (19a-19d) in the width direction of the outer column (11a-11d), with through holes formed in portions thereof that are aligned with each other; the slit (19a-19d) comprising: a main slit section (36, 36a-36c) formed in the axial direction and having a front end section in the axial direction and a rear end section in the axial direction; and a sub slit section formed in a circumferential direction of the front-end section in the axial direction of the main slit section (36, 36a-36c) in case that the outer column (11a-11d) is arranged on a rear side, or in a circumferential direction of the rear-end section in the axial direction of the main slit section (36, 36a-36c) in case that the outer column (11a-11d) is arranged on a front side, with the front or rear end section in the axial direction of the main slit section (36, 36a-36c) being open to a part in the circumferential direction of the sub slit section; characterized in that a length in the circumferential direction from the main slit section (36, 36a-36c) to one end section of both end sections of the sub slit section, which is in one half section in the width direction of the outer column (11a-11d) is longer than a length in the circumferential direction from the main slit section (36, 36a-36c) to the other end section which is in the other half section in the width direction of the outer column (11a-11d); a range where the slit (19a - 19d) is formed in the one half section in the width direction is larger than a range where the slit (19a - 19d) is formed in the other half section in the width direction, and the rigidity in the width direction of the one half section in width direction of the portion where the slit ( 19a - 19d) is formed is less than the rigidity in the width direction of the other half section in the width direction of the portion where the slit (19a - 19d) is formed.