The radiative effect of ozone on the quasi-biennial oscillation (QBO) is investigated with a chemistry-climate model. The model employs spectral T42 truncation and 68 layers, and contains major stratospheric chemical species including HOx, NOx, ClOx, and BrOx. Two control runs are designed to simulate the QBO with realistic period of the oscillation; the one with non-interactive ozone reproducing a 27-month period and the other with interactive ozone yielding a 31-month period. Two experiment runs are made by switching on and off the ozone radiative feedback for the non-interactive and the interactive control runs, respectively. The QBO period is prolonged from 27 to 48 months in the switched-on run, while it is shortened from 31 to 20 months in the switched-off run, demonstrating that the interactive ozone does prolong the QBO period. The elongation is primarily due to the fact that the QBO component of the solar heating cancels 1/3 to 1/2 of that of the terrestrial heating in the interactive ozone runs, yielding substantially weaker radiative heating than that in the non-interactive ozone runs.