privet loan

If those are the only facts, yes.  Of course, there are many things you don't mention which could change my answer, for example:        Will the debtor claim that the contract was modified or a new contract made after the signed paper?      Will the debtor claim the money was paid, in whole or part, or is not yet due?      Will the debtor claim that he/she signed the paper as a result of duress, mutual mistake, or fraud?      Will the debtor claim that he/she was too young, or otherwise lacked the capacity to contract when he/she signed?      Will the debtor claim that the agreement was illegal, for example that he/she was agreeing to pay you for sex, or to kill someone?      Will the debtor claim that his/her signature was forged?      Having a document signed by the debtor acknowledging his/her debt to you is a pretty good case, but I can't say for certain that you will win based on that paper without knowing whether the debtor has any defenses to your claim.