In a steering device having a steering lock device and a telescopic clamp device, the strength of a column in a key-locked state and the force of telescopic clamping are secured. A flange section and ribs are formed between a through hole which a lock pin comes in and leaves and a slit for reducing the inner circumferential diameter of an outer column so as to increase the strength of the outer column. Hence, both the strength of the outer column against the bending moment applied to the lock pin in a key-locked state and the strength of the outer column against telescopic clamping effected by reducing the inner peripheral diameter of the outer column can be secured.