An operating method for an inkjet head is disclosed. With a method of operating an inkjet head to eject ink droplets, for an inkjet head including a pressure chamber that is contracted and expanded in a particular period, a membrane included in one side of the pressure chamber, and a nozzle connected to the pressure chamber, where the method includes: (a) decompression-operating the membrane, such that the volume of the pressure chamber is increased, in correspondence with the period in which the pressure chamber is expanded; (b) compression-operating the membrane, such that the volume of the pressure chamber is decreased, in correspondence with the time point at which the pressure chamber is converted from an expanded state to a contracted state; (c) decompression-operating the membrane, such that the volume of the pressure chamber is increased, in correspondence with the period in which the pressure chamber is contracted; and (d) compression-operating the membrane, such that the volume of the pressure chamber is decreased, in correspondence with the time point at which the pressure chamber is converted from a contracted state to an expanded state, the operating waveform delivered to the actuator is designed in consideration of all of the resonance frequencies of the actuator, pressure chamber, and meniscus, whereby the ejection speed of ink droplets may be increased and the size of the ink droplets may be minimized, without being subject to the effects of resonance of the actuator during the process of ejecting the ink droplets.