A detergent supply apparatus comprising a storage space adjacent to a washing space in which washing is performed, a detergent bottle seat provided in the storage space and adapted to receive a detergent bottle containing a liquid detergent, a detergent reservoir in fluid communication with the detergent bottle, and a connecting part adapted to fix a portion of the detergent bottle to the detergent reservoir such that the liquid detergent can flow through the connecting part and into the detergent reservoir by gravitational force.