PURPOSE: To provide an alarm for bicycles hard to be broken even at the time of a fall for which the operation of a switch is facilitated, alarm whistle sound can be adjusted corresponding to the surrounding conditions and faults are few by changing the volume, tone and interval, etc., of the alarm whistle with pressurizing force to a pressure conductive switch.

CONSTITUTION: A prompt switching operation is enabled by tapping the upper surface of a handle bar with ease to touch the pressure conductive switch 5 and it is not necessary to search for the position of the switch as in the past. Also, the volume, tone and interval, etc., of the alarm can be adjusted by the strength when tapping the switch 5. The long-length pressure conductive switch 5 as indicated in a figure is desirable, however, the switch may be parted into plural pieces or may be short-length according to circumstances as long as it is provided in a position easy to be tapped by a hand. For instance, the installation position as well is not limited to the upper surface of the handle bar and the switch can be installed to the side surface and the lower surface.