A medication delivery device, for use with a container having a distal end and a needle being placed at the distal end of the container, including: a push rod which is movable with respect to at least a portion of the container； a resilient member configured to bias the push rod to move toward the distal end of the container； a releasable restraining means configured to releasably restrain the push rod in a locked state against the biasing of the resilient member； a means to adjust amount of movement of the push rod with respect to the container in order to deliver a predetermined dose of medication； and an activation means configured to release the releasable means. The means to adjust amount of movement of the push rod with respect to the container is bi-directional. The device can accommodate containers of different size or shape.
