A watch case for a wristwatch including a case middle having a central axis, a case back, bracelet attachment device removably connected to the case middle, and an annular ring rotatably mounted about the central axis of the case middle, the annular ring being provided with mechanical locking device capable, when the annular ring is in a locking position, of cooperating with complementary engagement device arranged on the bracelet attachment device, in order to secure the attachment device to the case middle. The annular ring is held between the case middle and the case back and the mechanical locking device include at least one resilient member, the member being elastically engaged with the complementary engagement device when the annular ring is in the locking position.