1. A method for generating an interpolation frame between a first reference frame and a second reference frame, comprising: dividing the interpolation frame into several interpolation areas containing several pixels; detecting a most correlated combination from several combinations between first reference areas and second reference areas for each of the interpolation areas, the first reference areas being in the first reference frame and having the same size and shape as the interpolation areas, the second reference areas being in the second reference frame and having the same size and shape as the interpolation areas, the each of the interpolation areas, the first reference area of each of the several combinations, and the second reference area of the each of the several combinations being arranged straight time-wise; obtaining a motion vector from the first reference area and the second reference area included in a detected combination; determining whether the first reference areas and the second reference areas are in a high-correlated area or a low-correlated area; giving the motion vector to the motion vector detected area, the motion vector detected area corresponding to the interpolation area which is determined to be the high-correlated area in the first reference area and the second reference area; determining a motion vector to be given to the motion vector undetected area by motion estimation using the motion vector undetected area, a first area, a third reference frame, a second area, and a fourth reference frame, the first area being in the first reference frame and being determined as the low correlated area, the third reference frame being in a direction temporally identical to the first reference frame with the interpolation frame as a reference, the second area being in the second reference frame and being determined as the low-correlated area; and the fourth reference frame being in a direction temporally identical to the second reference frame with the interpolation frame as a reference, the motion vector undetected area corresponding to the interpolation area which is determined to be the low-correlated area in the first reference area and the second reference area; and generating the interpolation frame based on the motion vector given to the motion vector detected area and the motion vector determined for the motion vector undetected area.