Provided is a motion vector detecting apparatus capable of detecting a motion vector of a pulldown-converted 3D image signal with high precision. A pulldown detecting unit detects whether a 3D image signal is a pulldown-converted image signal. An LR separating unit outputs an LR separation signal separated into left and right image signals in each of frames having the same image content. A frame delay LR separating unit outputs a frame delay LR separation signal separated into left and right image signals in a frame before one repetition period. A motion vector detector detects motion vectors of the left and right image signals, An LR combination unit combines the motion vectors of the left and right image signals to output the combined motion vectors as a motion vector.