An embedded system includes a nonvolatile memory, a control section, and a firmware update section. The nonvolatile memory stores firmware and a public key in a normal area, and stores a hash value concerning the public key in an access restricted area. The control section reads and executes the firmware from the nonvolatile memory. The firmware update section receives new firmware in which the hash value is encrypted and given as an electronic signature, and updates the firmware to the new firmware. The firmware update section is configured to: read the public key from the nonvolatile memory to calculate the hash value concerning the public key; when the hash value is identical to the hash value stored in the nonvolatile memory, calculate a hash value of the new firmware; decrypt the electronic signature with the public key to restore the hash value; and when these hash values are identical to each other, update the firmware.