To provide an electroosmotic pump which can prevent gas generated near an electrode from flowing to a downstream side and a liquid feeder using the electroosmosis pump.

In the electroosmotic pump 10A, a bubble separation member 40 is provided at an exit side chamber 28 so as to be separated from an exit side electrode 20; a gas vent member 42 is provided at that side section of a pump container 12 which is near the exit side electrode 20; and a gas vent member 44 is provided at that side section of the pump container 12 which is near an entrance side electrode 18. A self-filling mechanism 50 is placed in an entrance side chamber 26, and the self-filling mechanism 50 is composed of a liquid drawing member 52 in contact with an electroosmosis material 16 via the entrance side electrode 18, and of an air vent path 56 formed between a member 54 surrounding a side section of the liquid drawing member 52 and the inner wall of the pump container 12.