A burden distribution monitoring apparatus, according to the present invention, includes a hollow cylindrical sonde having an inner end radially movable within the internal space of a furnace, such as a shaft furnace. The sonde carries a burden layer depth sensor and/or a burden grain distribution sensor for radially shifting working ends of the sensors. With the foregoing construction, burden depth and/or grading of the burden can be monitored in a plurality of radial points in the furnace.