A white-light flare on 2001 March 10 was well observed in the H$\alpha$ line and Ca II$\lambda$8542 line using the imaging spectrograph installed in the Solar Tower Telescope of Nanjing University. Three small sunspots appeared in the infrared continuum image, one of which showed that the infrared continuum is enhanced by 4%-6% compared to the preflare value and it almost disappeared in the continuum image for about 3 min. Near the sunspot, there appeared a hard X-ray (HXR) source, the flux of which showed a good time correlation with the profile of the continuum emission. We propose that electron precipitation followed by radiative backwarming may play the chief role in heating the sunspot.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html