A door lock has an inner door assembly, an indoor doorknob assembly, and an outdoor doorknob assembly. The inner door assembly has a locking assembly casing. The indoor doorknob assembly has a positioning resilient component located in the locking assembly casing and configured to switch the door lock between a locked state and an unlocked state. The door is provided with enhanced protection by enclosing the positioning resilient component in the locking assembly casing, so the safety is further improved.