To provide a sound insulator for diminishing noise emitted from a loom without impairing operability, thus improving workplace environment.

The sound insulator (1) for the loom has five faces, i.e. front and rear and left and right faces and a top face with a bottom face open, and has a sound insulating cover (3) with its lower side sound insulating actuation position and upper side retreating position movable. In this insulator (1), the sound insulating cover (3) covers the space above a group of heddle frames (4) and the lower end (6) of the front face of the cover (3) is located at an angle of elevation of 45° or greater from a cloth fell (5) forwardly.