The invention relates to an automatic injection device (1) comprising: a container (6) provided with a needle (8); a housing (3) receiving a container (6) movable relative to said housing (3) between an initial position to an insertion position; a needle shield (12) for receiving said needle (8) and in which the needle (8) is embedded prior to use of said device (1); a deshielder (33) coupled to said needle shield (12) by first connecting means (51) and removably assembled to the distal part of the housing (3) by second connecting means (44, 45a, 45b, 57), characterized in that: said first and second connecting means are designed so that a rotational movement of the deshielder (33) about the device axis (2) of the device (1) with respect to the housing (3) causes an axial displacement of the needle shield (12) in the distal direction with substantially no rotational movement of the needle shield (12) with respect to the needle (8).