The president's @RealDonaldTrump account was closed around 07.00 pm (1130GMT).
In a statement, Twitter said: "Earlier today @realdonaldtrump’s account was inadvertently deactivated due to human error by a Twitter employee.
"The account was down for 11 minutes, and has since been restored. We are continuing to investigate and are taking steps to prevent this from happening again."
Users visiting Trump's account were left with the message of "Sorry, that page does not exist".
Twitter later said that the investigations revealed that the account was closed by a Twitter customer support employee on his last day of work.
"We are conducting a full internal review," the statement said.