A steering lock apparatus comprising: a steering column having a lock hole that is provided in a part of an outer circumferential surface of the steering column so as to pass through the steering column in a radial direction of the steering column; a key-lock collar that is supported by a portion of a steering shaft, which is supported on an inside of the steering column so as to be able to rotate freely, a phase of the portion in an axial direction of the steering column coinciding with the lock hole, and that has an engaging concave section provided in at least one location on the outer circumferential surface in a circumferential direction of the steering column; and a lock unit that is supported by and fastened to the steering column and that has: a butting surface that comes in contact with the outer circumferential surface of the steering column; a guide section that is formed on a tip end section of the butting surface and is located in an inside portion of the lock hole when the butting surface is in contact with the outer circumferential surface of the steering column; and a locking pin that essentially prevents rotation of the steering shaft when an ignition key is turned OFF by displacing inward in the radial direction of the steering column, causing the tip end section of the locking pin to engage with the engaging concave section; characterized in that a protruding wall section (17, 17a-d) is provided on the outer circumferential surface of the steering column so as to surround the lock hole; a concave groove is provided in a portion of the butting surface that surrounds the guide section, when the butting surface is in contact with the outer circumferential surface of the steering column, the protruding wall section (17, 17a-d) and the concave groove are engaged with each other. a steering column having a lock hole that is provided in a part of an outer circumferential surface of the steering column so as to pass through the steering column in a radial direction of the steering column; a key-lock collar that is supported by a portion of a steering shaft, which is supported on an inside of the steering column so as to be able to rotate freely, a phase of the portion in an axial direction of the steering column coinciding with the lock hole, and that has an engaging concave section provided in at least one location on the outer circumferential surface in a circumferential direction of the steering column; and a lock unit that is supported by and fastened to the steering column and that has: a butting surface that comes in contact with the outer circumferential surface of the steering column; a guide section that is formed on a tip end section of the butting surface and is located in an inside portion of the lock hole when the butting surface is in contact with the outer circumferential surface of the steering column; and a locking pin that essentially prevents rotation of the steering shaft when an ignition key is turned OFF by displacing inward in the radial direction of the steering column, causing the tip end section of the locking pin to engage with the engaging concave section; a protruding wall section (17, 17a-d) is provided on the outer circumferential surface of the steering column so as to surround the lock hole; a concave groove is provided in a portion of the butting surface that surrounds the guide section, when the butting surface is in contact with the outer circumferential surface of the steering column, the protruding wall section (17, 17a-d) and the concave groove are engaged with each other.