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):R2R1NCH2COCH2CH2COR3 (1)[wherein R1 and R2 each independently represent a hydrogen atom, an alkyl group, an acyl group, an alkoxycarbonyl group, an aryl group, or an aralkyl group； and R3 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.
