A magnesium alloy cast-rolling unit, including: a main body; a fluid supplier; an electric pushrod; a linkage mechanism; a horizontal platform; a screw; dovetail guide rails; and a bottom plate. The main body includes a base, a spring cylinder, a hydraulic adjustment cylinder, a connection portion, and a cast-rolling unit body. The connection portion includes an arc-shaped rail. The spring cylinder includes an actuation element. The actuation element includes a piston rod and a pressure strip. The piston rod includes an external thread at one end; and the pressure strip includes an internal thread corresponding to the external thread. The fluid supplier includes a head box, a corrugated pipe, a compression spring assembly including a gland cover, a connection pipe including a convex pipe joint and a concave pipe joint, a flat plate including a groove, a smelting furnace, and a horizontal operation platform.

A continuous casting start timing determination method, a continuous casting facility operation method, a slab manufacturing method, a determining device, a continuous casting start determination system, and a display terminal device are provided. A continuous casting start timing determination method for determining a continuous casting start timing includes: a measurement step of measuring temperatures in a copper plate of a casting mold in the continuous casting facility, by use of a plurality of temperature sensors provided in a casting-direction determination position as a predetermined casting-direction position on the copper plate; and a determination step of determining the start timing based on a casting-direction position of a molten metal surface of molten steel, the casting-direction position being estimated based on measurement results in the measurement step and a width of a slab to be cast in the continuous casting facility.