We present a lithographically made Al single-electron transistor that shows gate modulation at room
temperature. The temperature dependence of the modulation agrees with the orthodox theory,
however, energy-level quantization in a tiny metallic island affects the device characteristics below
30 K. The charge-equivalent noise of the device at 300 K was measured to be ;431022 e/Hz1/2 at
1 Hz and is expected to be 1000 times lower in the white-noise regime at higher frequencies.