The present invention provides a method of producing phosphoric acid crosslinked starch, including adding phosphorus oxychloride sequentially to raw starch slurry under a condition of pH 9 to 12 to cause the raw starch to undergo a phosphoric acid crosslinking reaction, and controlling the pH by sequentially adding an alkaline solution, wherein concentration of the alkaline solution is increased stepwise or continuously between start and end of the phosphoric acid crosslinking reaction. By the production method of the present invention, phosphoric acid crosslinked starch having a low phosphorus content and a high resistant starch content (for example, pea-derived phosphoric acid crosslinked starch, which has a resistant starch content of 80% or more according to a resistant starch measurement method of AOAC official method 2002.02 and a phosphorus content of 0.5% or less) can be obtained.