Abstract: A safety lock having an alarm function includes a transmitter positioned in a main lock body, and a remote receiver with an alarm function. The transmitter is placed in a stand-by state by microswitches activated either by a manually-operated fixing member or movement of latch pins in response to a key, and triggered by a microswitch responsive to full extension of a deadbolt. Under normal conditions, the deadbolt is stopped from fully extending by an adjustable stop, the position of which can be adjusted to adjust the clearance between an extension of the deadbolt and the third microswitch. When the first or second microswitch is activated and the deadbolt disengages from the stop due to an attempt to open the door by prying, cutting, or otherwise forcing the door open, the deadbolt extends fully and the third microswitch is caused to close, triggering the alarm.