The present disclosure includes a first counting member (4) arranged to display a counted number and biased to move in a first rotational direction, and a coupling member having a dose setting position and a dose dispensing position (5), in the dose setting position, the connecting member (5) prevents the first counting member (4) from rotating in the first rotational direction, and in the dose dispensing position, the connecting member (5) It relates to a counting mechanism (2) of the drug delivery device (1) that allows rotation of one counting member (4) in a first rotational direction.本開示は、計数された数を表示するように配置され、第１の回転方向に動くように付勢される第１の計数部材（４）と、用量設定位置および用量投薬位置を有する連結部材（５）とを含み、用量設定位置では、連結部材（５）が第１の計数部材（４）の第１の回転方向への回転を妨げ、用量投薬位置では、連結部材（５）が第１の計数部材（４）の第１の回転方向への回転を可能にする、薬物送達デバイス（１）の計数機構（２）に関する。
