The objectives of this study are to know the behavioural response of the hagfish, Paramyxine cheni to light and to find out if various parts of hagfish¡¦s body differ in sensitivity to light. Photosensitivity was measured in terms of time lapsed between light on and initiation of behavioural sequence (i.e., the reactive time). Behavioral response was measured by the persistent time from the beginning and ending of the behavioural sequence. Five types of light were used as the stimuli to the whole animal: green light, blue light, yellow light, red light, and white light. The lineup of sensitivity for various wavelengths in increasing reactive times( ranging from 13 seconds to 180 seconds) is: green light, blue light, white light, yellow light, red light. Red light significantly differed from the other four types of light in the reactive time; the hagfish was significantly less sensitive to this red light. Four regions of the body were tested with white light: head, gill aperture, tail and mid-portion between the first gill aperture to cloaca. In addition, two parts of the body were simultaneous tested with stimulate: head and tail (HT). The lineup of sensitivity of various regions of body for increasing reactive times (ranging from 9 seconds to 1200 seconds) is: tail, head, mid-portion between the first gill aperture to cloaca, and gill aperture. Tail was significantly more sensitive than the other three parts of the body. However, sensitivity for HT was significantly higher than the tail. Hagfish¡¦s spontaneous movement (i.e., under dark condition)included a number of behavioural sequences differed in the arrangement of behavior patterns (i.e., rolling, swimming, wiggling, springing, and pause). ¡¥Rolling¡¦ was the most preferred initial pattern in a spontaneous movement sequence. In contrast, illumination on tail evoked a complex motor response. Thus, such response was considered not a simple reflex, but a select of choice. ¡¥Swimming¡¦, on the other hand, is the most preferred initial pattern in the sequence triggered by photo stimulation on the tail. According to fluoresence histochemistry study the rhodopsin-like protein is present in the large oval-shaped cells distributed in the epidermis of hagfish. the number and the size of photo-sensitive cells on the tail and gill aperture and the fluorescence intensity on the tail were significantly higher than that on the gill aperture region.