A display apparatus comprising: a volatile memory ; a nonvolatile memory ; and a processor configured to: receive a user input to turn off the display apparatus from a user, prior to entering a power-saving mode, identify whether a system error occurs in the display apparatus by reading a stored value related to a system stability from one of the volatile memory or the nonvolatile memory , in response to receiving the user input, in response to identifying that the system error does not occur in the display apparatus , enter the power-saving mode while maintaining power supply to the volatile memory in which execution data regarding an application currently being executed is stored; and in response to identifying that the system error occurs in the display apparatus , perform a rebooting operation after storing execution status information of the application currently being executed in the nonvolatile memory , store, in the volatile memory , the execution data regarding the application which is obtained by executing the application by using application execution status information stored in the nonvolatile memory , and enter the power saving mode while maintaining the power supply to the volatile memory , wherein the stored value related to the system stability includes at least one of a value indicating whether the application currently being executed is operating normally, a value indicating whether a system internal memory is operating normally, a value indicating whether a system driver is malfunctioning, a value indicating whether a crash occurs between running applications, and a value indicating whether a reboot is required due to a software update. a volatile memory ; a nonvolatile memory ; and a processor configured to: receive a user input to turn off the display apparatus from a user, prior to entering a power-saving mode, identify whether a system error occurs in the display apparatus by reading a stored value related to a system stability from one of the volatile memory or the nonvolatile memory , in response to receiving the user input, in response to identifying that the system error does not occur in the display apparatus , enter the power-saving mode while maintaining power supply to the volatile memory in which execution data regarding an application currently being executed is stored; and in response to identifying that the system error occurs in the display apparatus , perform a rebooting operation after storing execution status information of the application currently being executed in the nonvolatile memory , store, in the volatile memory , the execution data regarding the application which is obtained by executing the application by using application execution status information stored in the nonvolatile memory , and receive a user input to turn off the display apparatus from a user, prior to entering a power-saving mode, identify whether a system error occurs in the display apparatus by reading a stored value related to a system stability from one of the volatile memory or the nonvolatile memory , in response to receiving the user input, in response to identifying that the system error does not occur in the display apparatus , enter the power-saving mode while maintaining power supply to the volatile memory in which execution data regarding an application currently being executed is stored; and in response to identifying that the system error occurs in the display apparatus , perform a rebooting operation after storing execution status information of the application currently being executed in the nonvolatile memory , store, in the volatile memory , the execution data regarding the application which is obtained by executing the application by using application execution status information stored in the nonvolatile memory , and <EOS>