A flash memory controller is suitable for a NAND flash memory and a voltage supply circuit. The voltage supply circuit supplies a current to the flash memory. The flash memory controller includes a flash control circuit, a current sensing circuit, and a processor. The flash control circuit is configured to control an operation of the flash memory. The current sensing circuit is configured to measure the current consumed by the flash memory during its operation, and output a current value. The processor is configured to output a control signal based on the current value. Therefore, the flash memory controller can instantly obtain a current value consumed during the operation of flash memory, and determine, based on the current value, whether the flash memory runs normally. A storage apparatus having the flash memory controller can instantly determine whether the flash memory runs normally.