A refrigerant amount inference apparatus infers a refrigerant amount in an air conditioner in which a compressor, a heat source side heat exchanger, a supercooling heat exchanger, a pressure reducing valve, and a use side heat exchanger are connected to piping. The supercooling heat exchanger exchanges heat between refrigerant that passes through a valve provided in a bypass circuit and refrigerant in a mainstream circuit. The refrigerant amount inference apparatus includes an acquiring unit that acquires a state of refrigerant in first piping provided between the pressure reducing valve and the supercooling heat exchanger and an operation amount related to the state of the refrigerant in the first piping, and a training unit that performs training by associating the state of the refrigerant in the first piping and the operation amount related to the state of the refrigerant in the first piping with a refrigerant amount.