Accurately characterizing the near-field electromagnetic distribution of millimeter-wave/terahertz (mmW/THz) devices under operational conditions is critical for advancing ultrafast communication and quantum technologies. However, existing passive terahertz near-field microscopy techniques face persistent challenges in achieving both high spatial resolution and broadband detection. Here, we propose a novel passive terahertz near-field microscope leveraging a nanoscale tip-integrated Josephson junction. By exploiting the AC Josephson effect in the probe, our system enables coherent detection across an ultra-wide bandwidth (1–300 GHz) with sub-picowatt-level power sensitivity. This approach simultaneously resolves near-field amplitude, frequency, and phase information while providing sub-wavelength spatial resolution. We demonstrate its efficacy by analyzing electromagnetic standing wave modes in superconducting microwave quantum circuits and mapping electromagnetic compatibility (EMC) characteristics in mmW oscillator chips. The proposed technique offers a breakthrough methodology for iterative design optimization of mmW/THz integrated circuits and performance diagnostics of superconducting quantum systems, bridging a critical gap in high-fidelity near-field characterization for emerging quantum and terahertz technologies.