To replenish a liquid supply mechanism having a plurality of liquid supply passages with liquid easily and efficiently.

Ink is supplied from a main tank 13 through a subtank 12 to a print head 11 through six supply passages. The supply passages are classified into first and second groups 81, 82 each provided with a tube pump 19a, 19b for generating a negative pressure in the subtank 12. When the subtank 12 is replenished with ink, a head tube enclosing valve 25 is closed and a negative pressure enclosing valve 26 is opened for the supply passages associated with the subtank 12 to be replenished with ink. The tube pump 19a, 19b for generating a negative pressure are then driven to reduce pressure in the subtank 12 thus replenished the subtank 12 with ink.