Provided is an enhancer for cancer thermotherapy not combined with photodynamic therapy. Cancer treatment not combined with photodynamic therapy is made available by using, as an enhancer for cancer thermotherapy, 5-aminolevulinic acids represented by formula (1): €ƒ€ƒ€ƒ€ƒ€ƒ€ƒ€ƒ€ƒR 2 R 1 NCH 2 COCH 2 CH 2 COR 3 €ƒ€ƒ€ƒ€ƒ€ƒ(1) [wherein R 1 and R 2 each independently represent a hydrogen atom, an alkyl group, an acyl group, an alkoxycarbonyl group, an aryl group, or an aralkyl group； and R 3 represents a hydroxy group, an alkoxy group, an acyloxy group, an alkoxycarbonyloxy group, an aryloxy group, an aralkyloxy group, or an amino group] or a salt thereof.
