  We present the relation of the spatial distribution of H-alpha kernels with
the distribution of hard X-ray (HXR) sources seen during the 2001 April 10
solar flare. This flare was observed in H-alpha with the (Sartorius) telescope
at Kwasan Observatory, Kyoto University, and in hard X-rays (HXRs) with the
Hard X-ray Telescope (HXT) onboard Yohkoh. We compared the spatial distribution
of the HXR sources with that of the H-alpha kernels. While many H-alpha kernels
are found to brighten successively during the evolution of the flare ribbons,
only a few radiation sources are seen in the HXR images. We measured the
photospheric magnetic field strengths at each radiation source in the H-alpha
images, and found that the H-alpha kernels accompanied by HXR radiation have
magnetic strengths about 3 times larger than those without HXR radiation. We
also estimated the energy release rates based on the magnetic reconnection
model. The release rates at the H-alpha kernels with accompanying HXR sources
are 16-27 times larger than those without HXR sources. These values are
sufficiently larger than the dynamic range of HXT, which is about 10, so that
the difference between the spatial distributions of the H$\alpha$ kernels and
the HXR sources can be explained.
