The present invention concerns a timepiece including a movement fitted with a power reserve indicator device, said timepiece including a barrel closed by a cover, a mainspring housed in said barrel and respectively connected to a barrel arbour and means for winding said mainspring, said indicator device including a differential gear kinematically connected by a first input to the barrel arbour, by a second input to the barrel and by an output to a power reserve indicator member and wherein the differential gear frame is arranged coaxially to the barrel arbour, characterized in that the second differential gear input is secured to the barrel cover, in that the differential gear output is formed by an inner toothed crown, in that the inner toothed crown is kinematically connected to the first input by at least first and second planetary wheel sets meshed with each other and in that the at least two planetary wheel sets are carried by the cover.