Promissory note is a written promise to pay a debt. It is a financial instrument, in which one party (maker or issuer) promises in writing to pay a determinate sum of money to the other (the payee), either at a fixed, determinable future time or on demand of the payee subject to specific terms.
Thus, a promissory note generally means a signed document containing a written promise to pay a stated sum to a specified person or the bearer at a specified date or on demand. A promissory note can be either payable on demand or at a specific time. If the promissory note is unconditional and readily salable, it is called a negotiable instrument.