A timepiece having an external case, a sound source disposed inside the external case, an internal filter that is gas permeable and waterproof and is disposed opposite with a gap to the external case and the sound source, and a communication opening that communicates the space between the external case and the internal filter with the outside. The internal filter is a porous thin film that has a large number of small holes and assures waterproofness preventing water from passing the small holes for at least ten minutes when in contact with water at normal pressure.