  We study topological objects in holographic QCD based on the Sakai-Sugimoto
model, which is constructed with $N_c$ D4 branes and $N_f$ D8/$\bar{\rm D8}$
branes in the superstring theory, and is infrared equivalent to 1+3 dimensional
massless QCD. Using the gauge/gravity duality, holographic QCD is described as
1+4 dimensional U($N_f$) gauge theory in flavor space with a background
gravity, and its instanton solutions correspond to baryons. First, using the
Witten Ansatz, we reduce holographic QCD into a 1+2 dimensional Abelian Higgs
theory in a curved space and consider its topological aspect. We numerically
obtain the Abrikosov vortex solution and investigate single baryon properties.
Second, we study a single meron and two merons in holographic QCD. The single
meron carrying a half-integer baryon number is found to have a infinite energy
also in holographic QCD. We propose a new-type baryon excitation of the
two-merons oscillation in the extra-direction of holographic QCD.
