Disclosed is an improvement in the process for the preparation of amorphous silicic acid particles useful, for example, as a filtration aid comprising the steps of a hydrothermal reaction to prepare calcium silicate particles and decalcification of the calcium silicate particles, after or without undertaking carbonation by the reaction of carbon dioxide, with an acid to form particles of amorphous silicic acid followed by drying of the amorphous silicic acid particles. Different from the conventional methods in which great shrinkage of the amorphous silicic acid cakes wet with water is unavoidable in the drying step to adversely affect the quality of the product, the final step of treatment preceding drying of the wet cake is undertaken in a liquid medium which is a mixture of water and a water-miscible organic solvent such as ethyl alcohol in a specified proportion so that the drying of the wet cake is performed without the disadvantage due to the large surface tension of water responsible to the drying shrinkage of wet cakes.