A device for automatic injection of a product into an injection site, said device comprising: - a housing (8, 19) capable of receiving a container movable relative to said housing (8, 19) between an initial position, in which a tip of a needle provided on the container does not extend beyond a distal end of said housing, to an insertion position, distally spaced relative to said initial position and in which the tip of the needle extends beyond said distal end of said housing, - triggering means upon which the user can exert a manual force for initiating the movement of the container from its initial position to its insertion position and automatic expelling of the product from the container, said triggering means being in one of a passive state, in which application of a force on said triggering means does not initiate said movement of the container, and an active state, in which application of said force on said triggering means does initiate said movement, and - a safety shield coupled to and movable with respect to said housing (8, 19) between a first position and a second position proximally spaced with respect to said first position, said safety shield having a free end that is distally spaced beyond a distal end of the needle when said safety shield is in said second position, movement of said safety shield from its first position to its second position by pressing the device against the user's skin placing said triggering means in its active state, characterized in that said device comprises: an indicator (19c, 13) that provides an indication to a user of the device that the safety shield has reached its second position, said indicator being formed by the cooperation of a first element located on said housing (19, 19b) and of a second element located on said safety shield, said first and second elements (19c, 13) cooperating together when said safety shield reaches its second position, so as to produce said indication, wherein said first element comprises at least a rib located on the inner wall of said housing and said second element comprises at least a tooth located at the proximal end of said safety shield, said tooth coming in contact with said rib and therefore producing a sound when said safety shield reaches its second position. - a housing (8, 19) capable of receiving a container movable relative to said housing (8, 19) between an initial position, in which a tip of a needle provided on the container does not extend beyond a distal end of said housing, to an insertion position, distally spaced relative to said initial position and in which the tip of the needle extends beyond said distal end of said housing, - triggering means upon which the user can exert a manual force for initiating the movement of the container from its initial position to its insertion position and automatic expelling of the product from the container, said triggering means being in one of a passive state, in which application of a force on said triggering means does not initiate said movement of the container, and an active state, in which application of said force on said triggering means does initiate said movement, and - a safety shield coupled to and movable with respect to said housing (8, 19) between a first position and a second position proximally spaced with respect to said first position, said safety shield having a free end that is distally spaced beyond a distal end of the needle when said safety shield is in said second position, movement of said safety shield from its first position to its second position by pressing the device against the user's skin placing said triggering means in its active state, an indicator (19c, 13) that provides an indication to a user of the device that the safety shield has reached its second position, said indicator being formed by the cooperation of a first element located on said housing (19, 19b) and of a second element located on said safety shield, said first and second elements (19c, 13) cooperating together when said safety shield reaches its second position, so as to produce said indication, wherein said first element comprises at least a rib located on the inner wall of said housing and said second element comprises at least a tooth located at the proximal end of said safety shield, said tooth coming in contact with said rib and therefore producing a sound when said safety shield reaches its second position.