A detergent supply apparatus and a washing machine having the same wherein residual water is not present in a liquid detergent containing unit. The detergent supply apparatus includes a detergent box and at least one liquid detergent containing unit provided in the detergent box to move a liquid detergent using a siphon phenomenon. The liquid detergent containing unit includes a siphon pipe to induce a siphon action, a siphon cap coupled to the siphon pipe, and at least one residual water hole formed through a bottom of the liquid detergent containing unit. The siphon cap includes at least one cap protrusion configured to be fitted into the residual water hole. A gap is defined between the residual water hole and the cap protrusion such that residual water is discharged from the liquid detergent containing unit through the gap.