An insole assembly for increasing the weight of footwear and a heavy footwear having an outsole and/or a midsole made of a high specific gravity compressed resin to enhance exercise effect. The insole assembly includes a lower insole made of a compressed resin having a high specific gravity; an upper insole laid on the lower insole and a shock-absorbing member attached to a heel of the lower insole. The insole assembly is made of a compressed resin to increase the weight of the footwear to which the insole assembly is applied.