Abstract: A arm wearable illuminating device comprises a bendable carrier, which is a bendable long-sheet-shape body; a plurality of illuminating element, which are evenly installed along long-axis direction of one side of the bendable carrier, and illuminate outwardly from the mounted surface; a transparent protective unit, which wraps the said bendable carrier and the said illuminating elements, and allows the emitting light from the illuminating elements transmitting through the transparent protective unit and displaying luminance; and a power supply device, which provides the electric power to the illuminating element for emitting light and controls the on-off status; thereby, the invention of the arm wearable illuminating device is operatively bendable for mounting on the arm, and is operatively stretchable for dismounting off the arm.