  We consider the classical fluctuations of the gravitational constant
generated by bubbles in the inflationary universe. For extended inflation, we
demonstrate numerically how and how large fluctuations are produced during
bubble expansion. The amplitude of the fluctuations depends on the Brans-Dicke
parameter $\omega$: if $\omega$ is of the order of unity, the amplitude becomes
of the order of unity within one Hubble expansion time; if $\omega$ is large
(say, $\omega=1000$), the growth rate of the fluctuations is small, but it
keeps growing without freezing during inflation. We also discuss some
astrophysical implications of our results.
