A flow amount measuring apparatus comprising: a rotating device, configured to rotate while material flows through the rotating device; a rotating bar, connected to the rotating device, configured to rotate corresponding to rotating of the rotating device; a feature acquiring device, configured to detect at least one feature of the rotating bar; and a computing unit, configured to compute a number for full rotations for the rotating bar based on the feature of the rotating bar, and configured to compute a flow amount for the material flows through the rotating device based on the number for full rotations.