A lock device that may be locked automatically includes a base fixed on a door plate. An actuating tube received in the hole of the base is provided with a locking member combined with a handle. The lock core unit has a lock core that may drive an actuating plate to rotate. The drive wheel has a drive slot for insertion of the actuating plate, so that the drive wheel and the actuating plate may be rotated simultaneously. An elastic member has two stop ends rested on the leg of the restoring wheel, and rested on the two sides of the ear plate of the locking plate. The drive plate has a first end inserted into an unlocking rotation knob of the other side of the door plate, and a second end inserted into the drive slot of the drive wheel.