It depends. If you are retirement age and have had the account for over five years then it should not be taxable. Double check the code(s) in box 7, of your 1099-R. The meaning of the codes are in the link below.
What Are Qualified Distributions? A qualified distribution is any payment or distribution from your Roth IRA that meets the following requirements. IRS Publication 590b
It is made after the 5-year period beginning with the first tax year for which a contribution was made to a Roth IRA set up for your benefit.