The lock body of a motorcycle disk brake lock has a first side, a second side adjacent to the first side, and an open slot of a predetermined depth and extending into the lock body, which is divided into a first portion and a second portion in which a locking device is disposed. The locking device is provided centrally with a locking bolt. When the locking device is in an unlocking state, the locking bolt is located at a first position. When the locking device is in a locking state, the locking bolt is located at a second position. The first portion is provided with an open end adjacent to the open slot and located in a locking hole coaxial with the locking bolt. The first portion is provided with at least one through hole having one end joining obliquely with the locking hole and having another end located in the side which is not adjacent to the open slot.