Controller Area Network (CAN) is widely employed as an in-vehicle network, and is required for extremely high reliability. CAN uses five mechanisms to detect errors caused by channel noises in CAN frames. However, an adversary can reportedly falsify a CAN frame by tampering with sample points in the frame. In this paper, the effectiveness of a new falsification method that does not require sample point tampering is proposed. In the method, transient electromagnetic pulses are injected into a CAN bus by magnetic coupling that enables falsification at the target CAN node without error detection. The proposed method was examined on a CAN bus which consists of two CAN nodes. As a result, the new falsification method was effective for CAN.