To provide an air pump for a bicycle which quickly injects the air of large capacity and with a high pressure to the bicycle tires.

The air pump for the bicycle is composed of an air storing container 5 to store the compressed air injected by a manual pump 30 via container injection passages 43b and 43a, air filling valves 44 and 49 for hindering the air stored in the container 5 from counterflowing toward the manual pump via the container injection passages 43b and 43a, air passages 43a and 43c extending from the container 5 and furnished at the forefronts with an air discharge hole 42 for injecting the air into the tires, and an opening/closing valve 44 to open and close the air passages 43a and 43c.