A century has passed since V. Hess discovered the cosmic-ray (CR) in
1912. Nature of CR was revealed soon through the discovery of the
east-west asymmetry effect, namely it consisted of mainly proton with
very high energy, and heavy nuclei were subsequently discovered as
well. In this talk, I overview the history of CRs from the view point
of particle physics, focusing upon the Brasil-Japan Emulsion Chamber
Collaboration in connection with the accelerator physics.  While
galactic CRs were discovered more than hundred years ago, the
acceleration and subsequent propagation mechanisms in the Galaxy are
still in open questions. I overview them briefly from the historical
point of view, and then present recent developments based on the
observational data, the 2-ry/1-ry ratio such as boron/carbon, isotopes
such as 10Be, antiproton, and electrons as well. I present the
diffusion halo model to understand them, what is consistent, and what
is inconsistent with each other.