The J-PARC linac accelerates a 50 mA H⁻ beam up to 400 MeV for user operation. To mitigate emittance growth caused by space-charge effects, transverse beam profiles are measured using wire scanner monitors (WSMs) for routine beam tuning. Tungsten is generally used as the wire material. However, the WSMs employ carbon nanotube (CNT) wires in the low-energy region between the RFQ and DTL, because the beam energy is low as 3 MeV and the thermal load is substantial. CNT wires were introduced in 2017 as a more heat-resistant alternative, and since then they have operated without replacement due to beam-induced damage, demonstrating excellent durability. In this study, we report beam profile measurements obtained with the CNT WSM at various beam energies.