A dental bulk block for machining, which is a glass-ceramic block including a crystalline phase in an amorphous glass matrix. The bulk block is a functionally graded material including crystalline phases where among the crystalline phases, a main crystalline phase is lithium disilicate, and an additional crystalline phase includes quartz, lithium phosphate, and at least one selected from among cristobalite and tridymite, in which the main crystalline phase has a size gradient with respect to a depth, and no interface is present at a point where a size gradient value of the main crystalline phase changes. Thus, the bulk block is useful in manufacturing artificial tooth prostheses that are similar to natural teeth and thus can not only reduce the time and processes for manufacturing artificial tooth prostheses but also obtain the effect of enhancing structural stability in terms of force distribution based on functionally graded mechanical characteristics.