1) Problem with ignition starter: If the ignition starter is faulty or damaged, it may cause a short circuit that will blow the fuse.
2) Problem with wiring: If the wiring to the ignition starter is damaged or corroded, it could cause a short circuit that will blow the fuse.
3) Faulty ignition switch: A faulty ignition switch can also cause the ignition starter fuse to blow.
If you are experiencing this issue, it is best to have the vehicle inspected by a qualified mechanic to determine the exact cause of the problem and have it repaired.