In a circuit board, when lands provided on a rear surface of a substrate are each separated into a mainland and a sub-land, warping or other defects of the substrate can be ignored when soldering, and the substrate can be mounted with a high bonding strength. The pressure block and operating rod are assembled in a groove of the main body. When the diversity mode is not required, the extra equalizer filter portions would represent a waste of power consumption andor chip space. The container is coupled to the housing within the chamber and configured to hold a liquid. The ink flow passage 18 is implemented as such an ink flow passage where ink in a high-concentration ink layer a formed in a lower area in the ink storage chamber 11 and ink in a low-concentration ink layer b formed in an upper area flow and merge as ink is supplied to the record head.