A tire pressure monitoring device of an electric vehicle includes a wheel speed sensor sensing a speed of each wheel of the electric vehicle, and a controller selectively calculating an intercept value of ΔFR and a cumulative average value of the ΔFR based on a difference between a torque of a front wheel motor and a torque of a rear wheel motor, calculating an intercept value of ΔLR and an intercept value of ΔDiag based on the speed of each wheel, and monitoring a tire pressure of each wheel based on the calculated intercept value of the ΔFR or the cumulative average value of the ΔFR, the calculated intercept value of the ΔLR, and the calculated intercept value of the ΔDiag.