PURPOSE: To make it possible not to obstruct the ink-supplying even when bubbles are immersed in a filter box and to suck without generating micro bubbles in the suction recovery timing by a constitution wherein an introduction opening and a discharge opening are opposed to a filter and are placed being opposed to each other.

CONSTITUTION: A recessed section 219 is provided to a circumference section so that bubbles remain in a position far from an introduction opening section in a stable condition. At that time, an ink flow for the ink-supply that acts against the bubbles in the recovery operation or the like is in a direction perpendicular to a direction of buoyancy of the bubbles and is different from a direction of a flow at a time when the bubbles are in a coaxial line between the introduction opening and a discharge opening. Thereby, deformation of the bubbles that may occurs when the bubbles is in the central portion of a filter, does not occur and at least one part of the bubbles existing between the filter 213 and an inner wall face having the introduction opening are passed through the filter 213 without becoming micro bubbles.