Exercise data apparatus for use on the body of a user during exercise, includes an electrocardiogram detector for detecting electrocardiogram data of the user during exercise; an attachment device for attaching the electrocardiogram detector onto the chest of the user; a motion detector for detecting body motion data indicative of steps of the user during exercise; a processor for calculating exercise data based on the electrocardiogram data detected by the electrocardiogram detector and the body motion data detected by the motion detector, the exercise data including at least one of heart rate, speed and distance, and calorie consumption of the user; and an output device for informing the user of the exercise data calculated.