The present invention is a honeycomb panel comprising metal face sheets respectively disposed on upper and lower faces of said honeycomb core characterized in that said honeycomb panel has a metal side plate disposed on at least one side face thereof, for mutually connecting honeycomb panels to each other, and a process for producing a honeycomb panel, said process characterized by comprising the steps of: welding a corrugated honeycomb core at an end face of its corrugation to a side plate along the end face of said corrugation; welding the honeycomb core at top portions of its corrugation to an upper face sheet from the side of the honeycomb core by means of an energy beam; welding bottom portions of the corrugation of the honeycomb core to a lower face sheet from the side of the face sheet by means of an energy beam; and welding the face sheets to the side plate before or after welding the honeycomb core to the face sheets.