Unconditional promise refers to a promise that is unqualified in nature. A party who makes an unconditional promise must perform that promise even though the other party has not performed according to the bargain. It is also termed as independent promise.
In the context of negotiable instruments, a promise or order is unconditional if it does not state an express condition to payment, if the promise or order is not subject to or governed by another record, or if the rights or obligations with respect to the promise or order are not stated in another record. [U.C.C. § 3-106]