A liquid ejection head having a plurality of ejection outlets for ejecting liquid; a first substrate and a second substrate for constituting a plurality of liquid flow paths in fluid communication with the ejection outlets, respectively when combined with each other; a plurality of energy conversion elements disposed in the liquid flow paths, respectively to convert electrical energy to ejection energy for the liquid in the liquid flow paths; a plurality of elements or electric circuits having different functions for controlling driving conditions of the energy conversion elements; wherein the elements and electric circuits are provided either on the first substrate or the second substrate, depending on their functions.