WATERPROOF TIMEPIECE

PROBLEM TO BE SOLVED: To provide large torque when the tightly fastened back lid of a timepiece is removed. SOLUTION: The rear end part of a timepiece frame 1 integrated out of an outer frame part 2 and a front cover part 3 is covered with a back lid 10. The back lid 10 is formed into a stepped vessel shape, a cylindrical part 10b is built up forward from the center part of a flange part 10a provided on the outer circumferential part, a pair of engaged parts 10c are formed in fixed ranges on the outer circumference of the cylindrical part, engaging parts 2e are formed in the vicinity of the rear end part of the outer frame part 2, and they are made into a screw pair and can be engaged with each other. A ring-like waterproof packing 11 is interposed between the rear end part of the outer frame part and the front face of the flange part, and when the back lid is screwed in, these three are tightly contacted with each other so as to be able to hold airtightness of the interior. A grasp part 10d projecting rearward from the back of flange part of the back lid is provided with a groove part 10e traversing the center part, and hence the lid can be easily opened by the use of a bar member such as driver.