The development of new blood vessels (angiogenesis) is important in the pathogenesis of rapid growth of solid tumors. Microangiography with a spatial resolution down to 8 μm was carried out at SPring-8 for the depiction of angiogenic vessels in a mouse model of cancer using a high-resolution image detector and a third-generation synchrotron radiation source. The new image detector is a fluorescent-screen optical-lens coupling system using a high-sensitivity pickup-tube camera. X-rays are converted into a visible image in a phosphor screen layer, and a visible light image is detected by the pickup tube. After analog-to-digital conversion, images are stored in a digital frame memory system with a 1024 × 1024-pixel and 10-bit format. In synchrotron radiation radiography, a long source-to-object distance and a small source spot can produce high-resolution images. A double crystal monochromator selected a single synchrotron radiation energy for imaging. Murine tumors had been transplanted into mice dorsal skin. Using a 9.0-keV monochromatic X-ray beam, small tumor blood vessels with diameters of 15 − 20 μm in an immature vascular network produced by angiogenesis were visualized after an iodine contrast material was injected into the common carotid artery.