To provide a fan selection device capable of selecting a fan using a small amount data prepared in advance and also using simple computations. A required ventilation flow quantity is computed by computing means 4 when predicted total electric power consumption and a predicted air temperature rise are entered into a predetermined computational expression. Parameter range determining means 5 determines a parameter range of a proper flow quantity ratio necessary for cooling. Required flow quantity computing means 7 computes a minimum required flow quantity and a maximum required flow quantity by dividing the required ventilation flow quantity by the upper and lower limit values of the parameter range of the proper flow quantity ratio, respectively. Selection means 8 searches for a fan that produces the maximum flow quantity necessary for obtaining a flow quantity that falls between the minimum required flow quantity and the maximum required flow quantity, from a database 9, and selects the fan as the required fan.