Disclosed are a manufacturing method of artificial light-weight aggregates which have an uniformed foaming property of the inside of the aggregates, and artificial light-weight aggregates by using a material which comprises reject ash by controlling the inserting temperature, heating speed, sintering temperature, and having low specific gravity and absorptance without adding separate blowing agent, fusing agent. The present invention relates to a manufacturing method of artificial light-weight aggregates by using a material which comprises reject ash and temperature elevation sintering method which comprises: (a) a step of inserting a material to a preheated firing furnace; (b) a step of elevating the temperature of the furnace in which the material is inserted; (c) a step of maintaining in the optimum elevated temperature after finishing the elevation of the temperature; (d) discharging the material which is finished sintering after maintaining for a predetermined time. [Reference numerals] (AA) Embodiment 1-4; (BB) Embodiment 5-8; (CC) Embodiment 9-12; (DD) Comparison example 1-4