To give a caution to persons who come in and out of a room to prevent stumbling by generating alarm sound which informs the existence of a difference in steps of a lower frame by an alarm sound generation device which is built in a door when a latch stored in such a manner that it can come out and in freely protrudes.

A hoisting original side of a door 1 which stores a latch 3 in such a manner that it can come in and out freely is supported on a longitudinal frame 2 in such a manner that it can be opened and closed freely. An alarm sound generator 6 consisting of an integrated circuit, a speaker, etc., is built in the door 1. A switch provided in the latch 3 is in an OFF condition when the door 1 is closed and is in an ON condition when it is opened to announce digital sound recorded in the integrated circuit in advance. The digital sound may be simple alarm sound such as buzzer. Moreover, the digital sound may be generated once or several times repeatedly. Consequently, it is possible to inform the existence of a difference in steps of a lower frame 4 and give a causation to persons who come in and out of a room through the door 1 to prevent stumbling and stepping off in advance.