A heating device for heating a workpiece, comprising: a furnace defining a closed space insulated from exterior and surrounded by a heat insulator, the furnace having a sidewall; a heater disposed in the furnace to heat a workpiece; horizontally spaced support elements for supporting a workpiece in the furnace, each support element comprising a horizontal bar; and horizontally arranged bases each holding two of the support elements, each base comprising: a horizontally planar portion; a columnar mounting portion extending downward from a part of the planar portion between the support elements, the mounting portion being directly mounted to the sidewall of the furnace or indirectly mounted to the sidewall of the furnace via an intervening structure; support element retaining portions extending upward from the planar portion, each support element retaining portion holding an end of the respective support element, the support element retaining portion being horizontally offset from the mounting portion; and at least one rib extending upward or downward from the planar portion to increase the strength of the base against deformation due to a load of the workpiece and/or support element applied through the support element retaining portion. a furnace defining a closed space insulated from exterior and surrounded by a heat insulator, the furnace having a sidewall; a heater disposed in the furnace to heat a workpiece; horizontally spaced support elements for supporting a workpiece in the furnace, each support element comprising a horizontal bar; and horizontally arranged bases each holding two of the support elements, each base comprising: a horizontally planar portion; a columnar mounting portion extending downward from a part of the planar portion between the support elements, the mounting portion being directly mounted to the sidewall of the furnace or indirectly mounted to the sidewall of the furnace via an intervening structure; support element retaining portions extending upward from the planar portion, each support element retaining portion holding an end of the respective support element, the support element retaining portion being horizontally offset from the mounting portion; and at least one rib extending upward or downward from the planar portion to increase the strength of the base against deformation due to a load of the workpiece and/or support element applied through the support element retaining portion. a horizontally planar portion; a columnar mounting portion extending downward from a part of the planar portion between the support elements, the mounting portion being directly mounted to the sidewall of the furnace or indirectly mounted to the sidewall of the furnace via an intervening structure; support element retaining portions extending upward from the planar portion, each support element retaining portion holding an end of the respective support element, the support element retaining portion being horizontally offset from the mounting portion; and at least one rib extending upward or downward from the planar portion to increase the strength of the base against deformation due to a load of the workpiece and/or support element applied through the support element retaining portion.