A refrigeration cycle system comprising a plurality of refrigeration cycle apparatuses connected in series by pipes with each other, each refrigeration cycle apparatus including: a refrigerant circuit in which a compressor, a first heat exchanger, a decompression device, and a second heat exchanger are connected with each other through refrigerant pipes, refrigerant circulates inside, and the second heat exchanger exchanges heat between the refrigerant and a heat medium; a casing housing the refrigerant circuit; a first heat-medium pipe including a first heat-medium bifurcation pipe for allowing the heat medium to flow into the second heat exchanger inside the casing; and a second heat-medium pipe including a second heat-medium bifurcation pipe for allowing the heat medium to flow out of the second heat exchanger inside the casing, the casing including a first frame body having such a tapered sectional shape in a vertical direction that an area of a lower surface part of the first frame body is smaller than an area of an upper surface part of the first frame body, and a second frame body having a rectangular sectional shape in the vertical direction and including a side surface part connected with a peripheral part of the lower surface part of the first frame body, the first heat-medium pipe including a first heat-medium inflow end part and a first heat-medium outflow end part, at least one of the first heat-medium inflow end part and the first heat-medium outflow end part being housed in the second frame body, the second heat-medium pipe including a second heat-medium inflow end part and a second heat-medium outflow end part, at least one of the second heat-medium inflow end part and the second heat-medium outflow end part being housed in the second frame body, the refrigeration cycle system comprising a pipe protection panel covering and protecting a front side, a back side, and an upper side of a pipe of the pipes, the pipe being positioned outside of the casing of each of the refrigeration cycle apparatuses. a refrigerant circuit in which a compressor, a first heat exchanger, a decompression device, and a second heat exchanger are connected with each other through refrigerant pipes, refrigerant circulates inside, and the second heat exchanger exchanges heat between the refrigerant and a heat medium; a casing housing the refrigerant circuit; a first heat-medium pipe including a first heat-medium bifurcation pipe for allowing the heat medium to flow into the second heat exchanger inside the casing; and a second heat-medium pipe including a second heat-medium bifurcation pipe for allowing the heat medium to flow out of the second heat exchanger inside the casing, the casing including a first frame body having such a tapered sectional shape in a vertical direction that an area of a lower surface part of the first frame body is smaller than an area of an upper surface part of the first frame body, and a second frame body having a rectangular sectional shape in the vertical direction and including a side surface part connected with a peripheral part of the lower surface part of the first frame body, the first heat-medium pipe including a first heat-medium inflow end part and a first heat-medium outflow end part, at least one of the first heat-medium inflow end part and the first heat-medium outflow end part being housed in the second frame body, the second heat-medium pipe including a second heat-medium inflow end part and a second heat-medium outflow end part, at least one of the second heat-medium inflow end part and the second heat-medium outflow end part being housed in the second frame body, the refrigeration cycle system comprising a pipe protection panel covering and protecting a front side, a back side, and an upper side of a pipe of the pipes, the pipe being positioned outside of the casing of each of the refrigeration cycle apparatuses.