The present invention relates to an automatic injection device (1) comprising: a container having a longitudinal axis A and movable between a first position and a second position, in which the needle is inserted, biasing means, for moving the container to its second position, retaining means (70, 73, 74) for maintaining said biasing means in a first stressed state, triggering means (90) for releasing said retaining means, said retaining means comprising a lever member having a pivoting part and a radial projection extending therefrom, said radial projection being in a first angular position when said retaining means is in its passive condition, said radial projection being in a second angular position, different from said first angular position, when said retaining means is in its active condition, the axis of said pivoting part being included in a transversal plane of said longitudinal axis A.