This paper intends to give a comprehensive survey of the development in the experimental study of "elementary particles" during the last four or five years. However, the most part of the paper has been devoted to the strongly interacting particles, bringing into discussion only a few problems concerning the weak interaction. The main reason for doing so is this: It is in the area of the strongly interacting particles that there has been in these years a rapid and large accumulation of newly discovered facts, that is, the resonant states of particles, quickly bringing the total number of particles from about 30 to about 100; moreover, in the corresponding theoretical aspect, there is also up to now a more or less successful development, that is, the SU(3) classification scheme as proposed from the symmetry of strong interaction. Simply because of these new developments, we are now more than ever certain that the so-called elementary particles are not elementary but composite, i.e. having internal structure (at least as far as the strongly interacting particles are concerned). This point has been discussed in some detail in the "Introduction". The paper then summari2es and discusses seven groups of experiments which have been performed in the last four or five years and are considered as more important in the field of "elementary particles", four groups being concerned with the strong interaction while three groups with the weak interaction. After this, discussion has been concentrated on the recent development of the strongly interacting particles, on the status of statistics before and after 1960, and on the physical meaning of the particle classification, etc. It is hoped that this will provide a physical background for discussing the classification schemes of SU(3) and the Regge trajectories. Finally, in discussing the two classification schemes, particularly the SU(3) scheme, effort has been made to explain with as much clarity as possible the physical background and the conjecture made, the mathematical basis, the theoretical results, and comparison with experiment. Comparison with experiment shows that the Regge trajectory scheme is not at all as satisfactory as the SU(3) scheme, this being naturally related with the serious difficulty as revealed by experiment (cf. Section II.3) of the theory of Regge poles. It is hoped that this paper may present a general picture of the recent development of "elementary particles", probably showing what problems have become clear and what still have not, and may possibly indicate the direction of future experimental research.