Although fetal hydrocephalus is commonly detected by prenatal ultrasonographic examination, posthemorrhagic hydrocephalus has rarely been observed in the fetus. We report a case of hydrocephalus secondary to intraventricular hemorrhage (IVH) diagnosed by in utero magnetic resonance imaging (MRI) at 37 + 1 weeks of gestation. Ultrasonography revealed enlargement of the bilateral ventricles and an irregular mass measuring 20 x 12 x 10 mm in the right lateral ventricle. T1-weighted images with two-dimensional fast low-angle shot (2D-FLASH) and T2-weighted images with half-Fourier single-shot turbo spin echo (HASTE) demonstrated that an old hemorrhagic clot existed in the right lateral ventricle of the fetus. Hydrocephalus secondary to IVH was confirmed by postnatal MRI and ventriculoscopy. Fast MRI is especially useful for prenatal diagnosis of fetal brain abnormalities because it minimizes the artifact of fetal movement.