The present invention relates to a method for manufacturing a zirconia block for a dental prosthesis having stratified color gradients based on a moisture absorption rate, wherein the particle sizes of powder are set differently layer by layer of a zirconia block and a degree of permeation of color solutions are adjusted based on a property where an amount of moisture absorption per time varies depending on particle sizes of powder, thereby enabling a product to have a color identical to that of a naturally-occurring material and have excellent aesthetics without conventional coloring liquid application for zirconia. More specifically, the method comprises: a main raw material separation step (S10) of grinding zirconia to have different particle sizes and sorting and preparing zirconia having different particle sizes, respectively； a supplementary raw material mixing step (S20) of putting a supplementary raw material enabling adjustment of a moisture absorption rate into each main raw material having different particle sizes, respectively and mixing the same； a raw material pressurization step (S30) of injecting the raw materials mixed with the supplementary raw materials into a mold for compression molding in order of particle sizes from the smallest to the largest or from the largest to the smallest and then compression-molding them into a block shape； a raw material coloring step (S40) of putting the molded zirconia block into a color solution-containing tank and applying heat to the block to induce the color solution to permeate the zirconia block； and a heat treatment finishing step (S50) of drying and calcining the color solution-permeated zirconia block with heat at room temperature.본 발명은 분말의 입도 크기에 따라 시간당 수분 흡수량이 차별되는 성질을 바탕으로 지르코니아 블록의 층별로 분말의 입도를 다르게 설정하여 색상용액의 침투 정도를 조절함에 따라 기존의 지르코니아용 컬러링 리퀴드 공정을 실시하지 않고도 자연치와 동일한 색상 및 심미성이 우수한 결과물을 구현할 수 있도록 구성되는 수분 흡수율에 의해 층별 색상 구배를 갖는 치아 보철용 지르코니아 블록의 제조방법에 관한 것으로, 더욱 상세하게는 지르코니아의 입도를 각각 차별되게 분쇄하고, 각기 다른 입도 별로 구분하여 준비
