A steering lock device (1) is for use with a steering shaft (5a) and includes a lock mechanism (11) that includes a lock bar (13), a housing (2) that includes an opening (3) and accommodates the lock mechanism (11), a cover (4) that closes the opening (3) of the housing (2), and one or more protective walls (40, 40a to 40d) arranged on the cover (34). The lock bar (13) locks the steering shaft (5a) when the lock bar (13) is moved to an engagement position where the lock bar is engaged with the steering shaft. The one or more protective walls (40, 40a to 40d) are located in one or more imaginary unauthorized access routes (A1, A2, A3, A4) to the lock mechanism (11) extending from outside the steering lock device (1).