An internal voltage generating apparatus adaptive to a temperature change includes a reference voltage circuit including a complementary to absolute temperature (CTAT) type transistor and a proportional to absolute temperature (PTAT) type transistor for generating a first to a third initial reference voltage signals. A buffer circuit for buffering a first, a second and a third initial reference voltage signal is included to generate a first, a second, and a third reference voltage signal in response to enable signals. An internal voltage generating circuit is included to generate an internal voltage signal based on the first, the second and the third reference voltage signal by using an inputted power voltage.