Abstract: The alarm device comprises a pulse timer which at varying, non-predictable time intervals supplies activation signals for ignition of a warning lamp (13) and activation of an acoustic alarm generator (19), if the driver has not within a predetermined time interval after ignition of the warning light (13) operated a selectively operable resetting contact (26). The pulse time is constituted by a counter (1) for which the frequency of the supplied counting pulses is switched over from a comparatively low value (f.sub.1) to a substantially higher frequency (f.sub.2) upon supplying the activation signal for ignition of the warning lamp (13). By operating the resetting contact (26) the counter (1) is stopped in the occupied counting position for a predetermined second time interval. At the expiry of said time interval the signal connection from the counter to the warning lamp is re-established and the counter (1) counts further from the occupied counting position with the comparatively low count pulse frequency (f.