Ferroelectric metal oxide crystalline particles are produced by first producing nanoparticles of a ferroelectric metal oxide and dispersing the nanoparticles in a gas phase. Then, the nanoparticles are processed by heat treatment with the nanoparticles being maintained in the gas phase in a dispersed state. The nanoparticles may be produced by using a laser ablation method. The ferroelectric metal oxide may have a perovskite crystal structure.