To obtain a lock for bag the whole body of which is attached to the outside of a bag.

The lock for bag has a structure that is vertically symmetric with respect to a center lock 5 and the figure shows the center lock 5 and a lower side lock 6. The center lock 5 has a cylinder lock 51 and moves the linkage 53 of the side lock 6 upward and downward by means of a cylinder cam 52. When the linkage 53 is set to a released state by moving the linkage 53 upward as shown in the figure, a lever 63 connected to the linkage 53 and the front-end retaining piece 62 of the lever 63 come off from the locking section 69 of a side lock cover 61. Therefore, the side lock 6 can be released by rotating the side lock cover 61. Since the connecting section between the center lock 5 and side lock 6 is attached to the outside of the case of the main body 1 of the bag, the whole body of the lock for bag can be attached to the outside of the case.