The utility model relates to a tool for ensuring that core bodies in building blocks are kept at the same height in the manufacturing process of heat preserving bricks, in particular to a core setter. The core setter comprises a core body and a mold, and is characterized by further comprising a frame body, wherein a pressing device is arranged on the upper part of the frame body; a guide rail on which trolleys walk is arranged on the middle part of the frame body; a trolley for conveying the core body is arranged on the guide rail; a trolley for conveying the mold is arranged on the lower part of the guide rail; the trolley for conveying the core body is provided with a through hole for installing the core body; and a mold support is arranged on the lower part of the trolley for conveying the core body. The core setter disclosed by the utility model has the beneficial effects that the core setter has higher accuracy than that of manual core setting, the problem of difference in core body heights caused by oblique manual core setting is solved, and the distances between the core body and the sides of the mold are the same.