Abstract: 
Provided is a refrigeration cycle device of which a decrease in performance due to an increase in pressure loss is suppressed, and by which a decrease in the drive performance of the refrigeration cycle device as a whole is prevented. The refrigeration cycle device 100 according to the present invention is provided with a refrigeration cycle which includes an evaporator 4 and through which a refrigerant circulates, wherein the refrigerant flows through the evaporator 4 at an average flow velocity u such that a function Tsat_u(u) is less than Tsat_u_min + 0.3(°C): where Q(W) is the amount of heat exchanged by the evaporator 4; d(m) is the refrigerant flow passageway diameter of the evaporator 4; Ai(m2) is the heating surface area inside the pipe of the evaporator 4; k(W/mK) is the average heat conductivity of the refrigerant; ρ(kg/m3) is the average density of the refrigerant; μ(Pa⋅s) is the average viscosity of the refrigerant; Pr is the Prandtle number of the refrigerant; u(m/s) is the average flow velocity of the refrigerant flowing through the evaporator 4; Tsat(u) is a function which is determined by the type of the refrigerant and which is used for deriving a refrigerant saturation temperature difference between an entry and an exit of the evaporator 4 from the average flow velocity u of the refrigerant flowing through the evaporator; and Tsat_u_min is the minimum value of the function Tsat_u(u) expressed by the expression (1).
