A needle bar stop device for a sewing machine in which a needle bar arm is separated into two parts, a first arm on a main shaft side, the rotation of which is controlled by a sub-shaft and a second arm on the needle bar side which is capable of rotating about the sub-shaft. An extended part is provided on either the first armor the second arm extending along the side surface of the other arm, and an insertion hole is formed in the extended part. An engaging hole is formed in the other arm so as to be capable of aligning with the insertion hole. A movable engaging member fitting in the insertion hole is part of a coupling mechanism that is selectively operated to cause the engaging member to engage with and disengage from the engaging hole.