A medicament delivery device comprising a) a medicament container holder for holding a medicament container comprising a medicament delivery member; b) a movable guard for covering the medicament delivery member, said movable guard being slidable along the medicament container holder between a proximal position and a distal position, wherein proximal is pointing to a dose delivery site, and distal is pointing away from the dose delivery site; c) an actuation locking member disposed opposite to the movable guard with respect to the medicament container holder and being slidable along the medicament container holder, the guard and the actuation locking member having at least one longitudinally extending tongue (12, 28); and d) a locking mechanism having a flexible lever which is pivotedly mounted at the medicament container holder and comprises a first portion being proximal from a pivotal axis of the lever and a second portion being distal from the pivotal axis of the lever, wherein the second portion has a ledge which is arranged to abut the longitudinally extending tongue of the actuation locking member for restricting movement of the actuation locking member until the movable guard is positioned in the distal position, and to be overlapped by the longitudinally extending tongue of the movable guard with tensioning the lever and allowing the actuation locking member to move in a proximal direction for actuation of the device when the movable guard is positioned in the distal position, and wherein the first portion is arranged to abut the movable guard for restricting movement of the guard in a distal direction after the device has been actuated, the movable guard has been moved in a proximal direction by a spring force, and the longitudinally extending tongue overlapping at least a part of the second portion of the lever. a) a medicament container holder for holding a medicament container comprising a medicament delivery member; b) a movable guard for covering the medicament delivery member, said movable guard being slidable along the medicament container holder between a proximal position and a distal position, wherein proximal is pointing to a dose delivery site, and distal is pointing away from the dose delivery site; c) an actuation locking member disposed opposite to the movable guard with respect to the medicament container holder and being slidable along the medicament container holder, the guard and the actuation locking member having at least one longitudinally extending tongue (12, 28); and d) a locking mechanism having a flexible lever which is pivotedly mounted at the medicament container holder and comprises a first portion being proximal from a pivotal axis of the lever and a second portion being distal from the pivotal axis of the lever, wherein the second portion has a ledge which is arranged to abut the longitudinally extending tongue of the actuation locking member for restricting movement of the actuation locking member until the movable guard is positioned in the distal position, and to be overlapped by the longitudinally extending tongue of the movable guard with tensioning the lever and allowing the actuation locking member to move in a proximal direction for actuation of the device when the movable guard is positioned in the distal position, and wherein the first portion is arranged to abut the movable guard for restricting movement of the guard in a distal direction after the device has been actuated, the movable guard has been moved in a proximal direction by a spring force, and the longitudinally extending tongue overlapping at least a part of the second portion of the lever.