To provide a water purifier capable of utilizing a performance of ion exchange resin filled into a cartridge, and to provide a humidifier using it.

Wide surfaces 46 for water path are provided on an upper surface and a bottom surface of a flat cartridge 19, and water passing length between both water passing surfaces 46 is shortened. A water introduction path 48 penetrating through both water passing surfaces 46 is provided on the cartridge 19. A space 54 for water introduction corresponding to the water passing surface 46 on the bottom of the cartridge 19 is provided on the water purifier equipped with the cartridge 19. Water is introduced into the space 54 through a water introduction path 48 from the upper part, and is allowed to flow from the bottom of the cartridge 19 towards the upper surface to be excellently purified.