According to an embodiment of the present disclosure, a spatial interpolation method for a linear phased array antenna relates to a spatial interpolation method for a linear phased array antenna including a plurality of transmission antenna elements and a plurality of reception antenna elements and includes Step 1 in which the plurality of reception antenna elements receive a reflected wave reflected from a target, Step 2 in which an incidence angle of the reflected wave incident on the plurality of reception antenna elements is estimated using an angle estimation algorithm, Step 3 in which a bad-conditioned antenna element is selected from among the plurality of reception antenna elements, and Step 4 in which a received signal of the bad-conditioned antenna element is compensated for and the incidence angle of the reflected wave incident on the plurality of reception antenna elements is re-estimated using an angle estimation algorithm.