An optical apparatus with dual illuminating devices includes a body, a first lighting device, a pivoting arm, an actuating pin, a switch and a second lighting device. The body has a joint portion. The first lighting device is mounted in the body. The pivoting arm has a first end and a second end. The first end is pivotally mounted on the joint portion so that the pivoting arm can be adjusted between a first position and a second position relative to the body. The second lighting device is mounted on the second end of the pivoting arm. Rotating the pivoting arm drives the actuating pin to press the switch, which turns off the second lighting device and turns simultaneously on the first lighting device.