PROBLEM TO BE SOLVED: To provide a lighting method for in-liquid investigation equipment and the in-liquid investigation equipment, capable of changing a view field of a camera independently of a posture of the in-liquid investigation equipment, capable of reducing the number of illumination units, capable of restraining a fluid resistance and a weight of an equipment body of the in-liquid investigation equipment from increasing, and capable of simplifying control. SOLUTION: This in-liquid investigation equipment 20 for investigating a liquid sealing state is arranged with the camera 25 and the illumination unit 26 in an inner side of transparent walls 21aa, 21ab formed in one part or the whole of the equipment body 21 of the in-liquid investigation equipment 20, and changes an illumination direction of the illumination unit 26 in linking with a direction of the view field of the camera 25, to conduct illumination. A non-light-transmitting partitioning wall 21b is further provided between the portion 21aa serving as a photographing view field of the camera 25 out of the transparent walls 21aa, 21ab in the in-liquid investigation equipment 20 and the portion 21ab with an illumination light transmitted therethrough, to prevent the light from being propagated in insides of the transparent walls 21aa, 21ab. COPYRIGHT: (C)2010,JPO&INPIT
