A broad emission band spectrum was observed at 192.7 nm by passing dc discharge through low pressure argon gas with aluminum electrodes. The relative spectral intensity distribution of the band was estimated by calibrating the monochromator system by means of the molecular branching ratio method and was then compared with the theoretical result by Sato et al. The origin of the band was further investigated experimentally. All the results strongly suggest that the observed broad emission band originates from the ArAl+ excimer.