Disclosed herein is to a posture monitoring device for measuring and correcting a user's posture by utilizing a resistance element which is elastic and has a resistance which is changed according to mechanical strain. The posture monitoring device includes a first elastic resistance element and a second elastic resistance element which are configured to be attached onto skins of the first part and the second part or inserted into the skins, disposed to measure the degree of stretching of the skin of the first part in a longitudinal direction of the spinal column, and made of a conductive material to have elasticity, a power supply device for applying a current or a voltage to the first elastic resistance element, and the second elastic resistance element, and a communication module for transmitting data output from the first elastic resistance element and the second elastic resistance element to a controller.