To provide a temperature distribution equilibrating device by which no variability occurs in the dimensions of moldings and no distortion of moldings, short molding, burrs and the like occur and further, the molding efficiency can be increased.

Running paths 12b, 12c and 13b for running a fluid are provided. In addition, a mold 11 having a cavity part into which a molten plastic is injected or blown, a feed mechanism 21 for supplying the fluid which cools or heats the mold 11 and a switching mechanism 31 which returns the fluid supplied from one end 13y of the running path 13b to the feed mechanism 21 by supplying the fluid supplied from the feed mechanism 21 to the other end 13x of the running path 13b of the mold 11 and returns the fluid supplied from the other end 13x of the running path 13b to the feed mechanism 21 by supplying the fluid supplied from the feed mechanism 21 to one end 13y of the running path 13b of the mold 11 through a return switching operation to be performed every specified time, are provided.