A first detecting means for detecting the phase of an hour time wheel and a second detecting means adapted to cooperate with a projection provided with each of some of a plurality of minute indication leaves, said some leaves occurring at a constant interval, are provided. The first and second detecting means are associated together, and with detection of phase by the first detecting means the second detecting means is rendered capable of cooperation with the projection of a minute leaf. Subsequently, when the phase of the projection is detected by the second detecting means, an alarm device is operated.