A running data display unit (1) for a bicycle calculates running data such as running speed, running distance, average speed, maximum speed etc. of a bicycle, based on pulse signals from a revolution detecting portion (3). This calculation is performed by a microcomputer incorporated in the display unit. The running data obtained by the calculation are displayed in a digital form on a liquid crystal display panel (15). The liquid crystal panel (15) also makes display of a pulse mark (26). The display of the pulse mark (26) turns on and off alternately at the rise of the pulse applied normally from the revolution detecting portion (3). As a result, by the display of the pulse mark (26), the rider of the bicycle can ascertain normal operation of the display unit (1), particularly normal operation of the revolution detecting portion (3). W