A medicament delivery device (1-1; 1-2; 1-3) comprising: a housing having a proximal end and a distal end, a medicament delivery member cover received by and rotationally interlocked with the housing, wherein the medicament delivery member cover is axially displaceable between an extended position relative to the housing and a retracted position, wherein the medicament delivery member cover is biased towards the extended position, a plunger rod axially biased towards the proximal end of the housing, a tubular rotator comprising a guide structure arranged to interact with the medicament delivery member cover and to convert linear motion of the medicament delivery member cover to rotational motion of the tubular rotator, wherein the tubular rotator is rotatable relative to the housing, and which tubular rotator is arranged to receive the plunger rod, and a sensor arrangement axially biased towards the proximal end of the housing, which sensor arrangement abuts a profiled distal edge periphery of the tubular rotator, and is able to follow the profile of the profiled distal edge periphery when the tubular rotator rotates so as to allow distinction between different stages of medicament administration; wherein the profiled distal edge periphery is arranged to interact with the sensor arrangement for actuating the sensor arrangement; wherein the tubular rotator is initially arranged in a first rotational position in the extended position of the medicament delivery member cover, in which first rotational position the tubular rotator is arranged to prevent axial displacement of the plunger rod, wherein the guide structure is arranged to allow the tubular rotator to rotate from the first rotational position to a second rotational position by axial displacement of the medicament delivery member cover towards the retracted position, thereby allowing release of the of plunger rod, and wherein the guide structure is arranged to allow the tubular rotator to rotate to a third rotational position distinct from the first rotational position by axial displacement of the medicament delivery member cover from the retracted position to the extended position, wherein the profiled distal edge periphery comprises a distinct elevation level for each of the first rotational position, the second rotational position and the third rotational position, and is structured so that the sensor arrangement is axially displaced by rotation of the tubular rotator from the second rotational position to the third rotational position, thereby providing an indication of medicament administration. a housing having a proximal end and a distal end, a medicament delivery member cover received by and rotationally interlocked with the housing, wherein the medicament delivery member cover is axially displaceable between an extended position relative to the housing and a retracted position, wherein the medicament delivery member cover is biased towards the extended position, a plunger rod axially biased towards the proximal end of the housing, a tubular rotator comprising a guide structure arranged to interact with the medicament delivery member cover and to convert linear motion of the medicament delivery member cover to rotational motion of the tubular rotator, wherein the tubular rotator is rotatable relative to the housing, and which tubular rotator is arranged to receive the plunger rod, and a sensor arrangement axially biased towards the proximal end of the housing, which sensor arrangement abuts a profiled distal edge periphery of the tubular rotator, and is able to follow the profile of the profiled distal edge periphery when the tubular rotator rotates so as to allow distinction between different stages of medicament administration; wherein the profiled distal edge periphery is arranged to interact with the sensor arrangement for actuating the sensor arrangement; wherein the tubular rotator is initially arranged in a first rotational position in the extended position of the medicament delivery member cover, in which first rotational position the tubular rotator is arranged to prevent axial displacement of the plunger rod, wherein the guide structure is arranged to allow the tubular rotator to rotate from the first rotational position to a second rotational position by axial displacement of the medicament delivery member cover towards the retracted position, thereby allowing release of the of plunger rod, and wherein the guide structure is arranged to allow the tubular rotator to rotate to a third rotational position distinct from the first rotational position by axial displacement of the medicament delivery member cover from the retracted position to the extended position, wherein the profiled distal edge periphery comprises a distinct elevation level for each of the first rotational position, the second rotational position and the third rotational position, and is structured so that the sensor arrangement is axially displaced by rotation of the tubular rotator from the second rotational position to the third rotational position, thereby providing an indication of medicament administration.