In the single-phase AC commutator motor (known as a universal motor), which is widely used in cleaners, electrical machines, etc., some problems generated by commutation sparks are wear on the brush and noise impediments. We have therefore attempted to use a high-speed camera to elucidate the commutation spark mechanism visually. The high-speed camera that we used is capable of photographing at 5,000 - 20,000,000 frames/s. Selection of a trigger module can be obtained from the operation unit and the exterior triggering signal. In this paper, we proposed an exterior trigger method that involved opening a hole of several millimeters across in the motor and using argon laser light, so that commutator segments may be photographed in position; we then conducted the experiment. This method enabled us to photograph the motor's commutator segment from any position, and we were able to confirm spark generation at every other commutator segment. Furthermore, after confirming the spark generation position of the commutator segment, we next attempted to accelerate the photographing speed to obtain more detailed photography of the moment of spark generation; we then prepared our report.