We introduce a novel contrast mechanism for imaging blood flow by use of magnetomotive optical Doppler tomography (MM-ODT), which combines an externally applied temporally oscillating high-strength magnetic field with ODT to detect erythrocytes moving according to the field gradient. Hemoglobin contrast was demonstrated in a capillary tube filled with moving blood by imaging the Doppler frequency shift, which was observed independently of blood flow rate and direction. Results suggest that MM-ODT may be a promising technique with which to image blood flow.