A casing of a webcam improves the hand feel of turning a lens ring. A base of the casing includes a sheath hole having a first connection portion, a first ring-shaped flange formed around an upper side of the lens ring, a second connection portion formed between upper and lower sides of the lens ring, and a second ring-shaped flange formed around the lens ring and abutted against an upper side of the sheath hole and a lower side of the first connection portion, and the first and second ring-shaped flanges of the lens ring are separated from the sheath hole by an interval. A flexible ring is clamped between the first and second connection portions and disposed between the first and second ring-shaped flanges, such that the casing can have a greater manufacturing tolerance to reduce manufacturing costs, and provide a better hand feel of turning the lens ring.