Recently, an interesting phenomenon has been reported in (K,Na)NbO3 (KNN)-based ceramics. That is the growth of huge grains (10-30 mm) which is a kind of abnormal grain growth (AGG). It was also interesting that the huge grains showed the stack of plate-type grains. Using one of those compositions, therefore, seed plates were synthesized by not topochemical reaction but simple molten salt synthesis (SMSS) which was a simple-and-cheap process. The calcined K0.4925Na0.4925Ba0.0165Nb0.998O3.004 (KNBN) powders and KF powders were heat-treated at 1050 degrees C-1150 degrees C. The seed crystals showed the (100)(C)-oriented structure. The size of seed plates was smaller than 500 m and one layer of a thin plate-type grain might show the thickness of 50 nm. They might be useful as the seeds at RTGG or TGG process.