An inkjetting apparatus includes a nozzle module, a driving module, and a membrane. The nozzle module includes an ink chamber for reserving ink, and a nozzle hole for permitting ink in the ink chamber to be jetted therethrough. The driving module includes a working fluid chamber, and a heater located in the working fluid chamber. The membrane serves as a partition between the ink chamber and the working fluid chamber. The membrane includes an ink injecting hole for interconnecting an ink injecting passage through which the ink is fed from an external ink source, with the working fluid chamber, and an interconnecting hole for interconnecting the working fluid chamber with the ink chamber to permit ink in the working fluid chamber to be fed into the ink chamber. The ink injecting hole and/or the interconnecting hole have neck modules for narrowing the ink injecting hole and/or the interconnecting hole to a size smaller than the inner diameters of the ink chamber and the working fluid chamber, respectively. Due to the presence of the neck modules, the sizes of the ink injecting hole and/or the interconnecting hole are smaller than the inner diameters of the ink flowing passage, so that any back flow of ink is prevented during the ink jetting process.