A heat exchanger structure of an automatic transmission stabilizing a temperature of oil is provided. A heat exchanger structure of an automatic transmission includes an automatic transmission, a first heat exchanger provided on an upstream side and a second heat exchanger provided on a downstream side, each capable of cooling oil ejected from the automatic transmission, and a thermo valve capable of supplying oil subject to heat exchange by at least one of first and second heat exchangers to the automatic transmission. When a temperature of the oil is relatively low, the thermo valve supplies oil passed through the first heat exchanger to the automatic transmission and shuts off a flow of oil from the second heat exchanger to the automatic transmission. When a temperature of the oil is relatively high, the thermo valve supplies oil passed through first and second heat exchangers to the automatic transmission.