A needle plate for a sewing machine includes a first needle plate fixed to a sewing machine bed and formed with a needle hole through which a needle passes and a rectangular hole through which a feed dog appears, a second needle plate disposed in front of the first needle plate and detachably attached to the first needle plate, an engagement mechanism sliding the second needle plate rearward from a front side of the first needle plate, thereby engaging the second needle plate with the first needle plate, and a disengagement operating member located on the second needle plate so as to operate the engagement mechanism so that the second needle plate is disengaged from the first needle plate. The disengagement operating member is moved frontward from a rear side of the first needle plate thereby to disengage the second needle plate from the first needle plate.