To provide a rotational inertial force increasing member and a driving wheel of a bicycle having the same, with a simple and inexpensive constitution, for increasing rotational inertial force, without largely increasing required torque when starting the bicycle.

This rotational inertial force increasing member is arranged in the driving wheel of the bicycle having a hub, the rim and a spoke for fixing the hub and the rim, and increases the rotational inertial force of the driving wheel by rotating by rotation of the driving wheel, and is arranged in at least one of a shaft part of the hub, the rim and the spoke, and is characterized in that its arranging position is nearer to the hub than a gravity center position in the radial direction of the driving wheel.