A power system monitoring and control system having a thread-dependent calculation monitoring function comprising: a display unit displaying screen information; a calculation handling unit executing thread-dependent calculation based on a calculation expression defined in a calculation file; and a data storage unit storing file information for power system monitoring and control, information on the calculation file, calculation result information, and thread-dependent calculation execution monitoring information, wherein the calculation handling unit includes a calculation execution monitoring information display handling unit, the calculation execution monitoring information display handling unit generating the thread-dependent calculation execution monitoring information for monitoring calculation execution and enabling the generated thread-dependent calculation execution monitoring information to be displayed on the display unit, wherein, in order to provide to a user a notification that the calculation is being correctly performed, the thread-dependent calculation execution monitoring information, in relation to the calculation files registered with the data storage unit, displays on the display unit: one or more of a calculation status indication, a registration file name, a registration account, a registration time, a time when calculation is performed, the number of all calculation expressions defined in a file, and the number of calculation expressions having errors while calculation is performed, wherein the calculation status indication is displayed in a different color according to an operation status of a calculation execution. a display unit displaying screen information; a calculation handling unit executing thread-dependent calculation based on a calculation expression defined in a calculation file; and a data storage unit storing file information for power system monitoring and control, information on the calculation file, calculation result information, and thread-dependent calculation execution monitoring information, wherein the calculation handling unit includes a calculation execution monitoring information display handling unit, the calculation execution monitoring information display handling unit generating the thread-dependent calculation execution monitoring information for monitoring calculation execution and enabling the generated thread-dependent calculation execution monitoring information to be displayed on the display unit, wherein, in order to provide to a user a notification that the calculation is being correctly performed, the thread-dependent calculation execution monitoring information, in relation to the calculation files registered with the data storage unit, displays on the display unit: one or more of a calculation status indication, a registration file name, a registration account, a registration time, a time when calculation is performed, the number of all calculation expressions defined in a file, and the number of calculation expressions having errors while calculation is performed, one or more of a calculation status indication, a registration file name, a registration account, a registration time, a time when calculation is performed, the number of all calculation expressions defined in a file, and the number of calculation expressions having errors while calculation is performed, wherein the calculation status indication is displayed in a different color according to an operation status of a calculation execution.