Takehiko Nakao, who began his second term as president of the Manila-based development bank today, also said there is a strong case for regional agreements to liberalize trade and investment despite Trump's threat to withdraw from the 12-nation Trans-Pacific Partnership.
Nakao made the comments in response to questions about what would happen if Trump ends the current US administration's emphasis on the region and pulls out of the TPP, which Trump called a "disaster" for American jobs.
"It's important for the US to continue to engage in Asia and that is good for the Asian region as a whole and it should be in the interest of the United States," he added.
The ADB chief cautioned that "it is too early to tell" what Trump's policy will be.
Leaders of the 21-member Asia Pacific Economic Cooperation forum ended their annual summit Sunday with a call to resist protectionism amid signs of increased skepticism about free trade, highlighted by Trump's victory in the US presidential election.