Bias effects on the deposition of hydrogenated amorphous silicon (a‐Si:H) film in the glow discharge were investigated by triode system which can control the negative bias without changing the other deposition conditions. The growth rate, H content, and photoconductivity of the film deposited at the substrate temperature 300–320 °C increased with the negatively enhanced bias. The results would be due to the enhancement of  ion flow by the bias and show that the bias has an advantage for the improvement of thea‐Si:H film characteristics.