A door deadbolt device that can prevent a door from opening operates independently from the lockset installed on the door. The device is easily locked from the inside of the room with a one-handed motion using an insertable tool or key which may be carried separately or stored out of the reach of small children or unauthorized persons. The bolt is positioned so as to be pushed into a locking position under the tension of a spring, thereby easily and securely bolting the door. The present invention further allows the user to rapidly unbolt the door from inside the room also with a one-handed single motion. Optionally, the device can also be unbolted from the outside with a special tool.