After a brief review of (holographic) entanglement entropy, we will first introduce our latest result on a thermodynamical property of entanglement entropy for excited states. Later, we study a conjectured connection between the AdS/CFT and a real-space quantum renormalization group scheme, the multi-scale entanglement renormalization ansatz (MERA). By making a close contact with the holographic formula of the entanglement entropy, we propose a general definition of the metric in the MERA in the extra holographic direction, which is formulated purely in terms of quantum field theoretical data.