The sportswear giant is IAAF’s largest sponsor and it is believed that the decision is a direct result of the doping scandal sweeping the sport.
Neither organisation would confirm the split to the BBC, but both issued short statements referencing the "reform process" under way.
An statement from the sportswear giant says: “As you know Adidas has a clear anti-doping policy in place. Therefore, we are in close contact with the IAAF to learn more about their reform process.”
The sponsorship deal was due to run until 2019 and was reportedly worth $33m (£23m), although some sources say the figure is much higher.