A fluid observation apparatus 20 can perform a method for observing a fluid by PIV. The method for observing a fluid includes capturing an image of inorganic particles in a fluid for flow observation 30 by irradiating the fluid for flow observation 30 passing through a flow channel with light, the fluid for flow observation 30 containing inorganic particles to be observed each having a planar surface, a dispersion medium to be observed, and a viscosity modifier. The fluid for flow observation 30 is high-viscosity non-Newtonian slurry containing inorganic particles. The fluid for flow observation 30 may be a simulated fluid for a fluid for flow analysis. The simulated fluid closely resembles the particle size of inorganic particles to be analyzed and the viscosity of the fluid for flow analysis. The fluid for flow analysis contains the inorganic particles to be analyzed and a dispersion medium to be analyzed.