A waterproof controller used for electric power steering includes a shell, a chamber, at least one sealing block, a circuit board, at least one cable, and at least one board mounting accessory. The chamber is formed in the shell. The sealing block is disposed on the shell, and includes at least one hole. The circuit board is accommodated in the chamber. The cable includes a first terminal and a second terminal opposite to the first terminal. The first terminal passes through the hole of the sealing block. The board mounting accessory covers the second terminal, in which the board mounting accessory and the second terminal insert into the circuit board together.