According to one embodiment, a magnetic resonance imaging apparatus includes a correction data acquisition unit configured to perform diffusion weighted imaging to a phantom having a known apparent diffusion coefficient and measure an apparent diffusion coefficient of the phantom to acquire correction data from a measured apparent diffusion coefficient and the known apparent diffusion coefficient, and an image generating unit configured to perform diffusion weighted imaging to an object with a same parameter setting as that of the diffusion weighted imaging to the phantom to generate an apparent diffusion coefficient image from a diffusion weighted imaging data of the object and the correction data.