Physical and dynamical states of astrophysical objects are quite different from those on the Earth. In this textbook, the interactions among gases, magnetic fields, and radiation fields in astrophysical environments are described from the viewpoint of astrophysical fluid dynamics. The current volume, which is its second edition, is intended for readers in advanced undergraduate and graduate courses of astrophysics and for young astrophysicists. Before describing astrophysical fluid dynamics, the authors briefly mention physical and dynamical situations to be treated in astrophysical fluid dynamics in Chapter 1. Following this introduction, the textbook is divided into four parts. In Part I, fundamentals of astrophysical fluid dynamics are reviewed, including various wave phenomena and instabilities, as well as special and general relativistic hydrodynamics (GRHD). In Part II, the interactions between gases and magnetic fields on fluid motions, i.e., magnetohydrodynamics (MHD), are reviewed by emphasizing how magnetic fields are important in understanding dynamical phenomena in astrophysical environments. General relativistic MHD (GRMHD) is also mentioned briefly. Part III is devoted to the effect of radiation fields on fluid motions—radiation hydrodynamics (RHD) highlighting hydrodynamical phenomena where radiation and gas motions are coupled. Cases in which high-energy photons and gases interact in general relativistic fields (GRRHD) are also outlined. In Part IV, as an aspect of interdisciplinary fields of astrophysical fluid dynamics, equations describing particle dynamics are briefly mentioned. High-energy elementary processes among particles and photons, which are necessary for describing RHD, are also explained.