Optical images of self-quenching streamers (SQSs) in a gas counter has been observed for charged particle incidents, α- and β-rays. Individual images of the streamers were obtained by using an image-intensifier system with a gating function. The observation was performed from the axial direction of the gas counter used. For α-ray irradiation, streamers develop only in two specific directions orienting primary-ionization tracks formed by α-rays. On the other hand, for β-rays, streamers grow in various directions; obtained images are similar to those for X-rays. On the basis of the observation, SQS-formation mechanisms by different sorts of ionizing radiation are discussed. A possible mechanism of 'PRimary-Ionization Track ORiented (PRITOR) type SQS' induced by α-ray is proposed.