A high-voltage discharge lamp illumination device comprises a pulse generation part which generates pulse waves, and a power supply part which receives a DC voltage and converts the DC voltage into the AC current in correspondence to a frequency of the pulse waves so as to supply the AC current to the lamp. The pulse generation part repeats a cycle of outputting a first pulse wave over a first period, and thereafter outputting a second pulse wave having a lower frequency than the first pulse wave over a second period shorter than the first period. The pulse generation part returns to the cycle after outputting a third pulse wave having a frequency which is further lower than the second pulse wave in place of the second pulse wave, at a predetermined timing.