Image forming apparatus, control method therefor, and storage medium storing control program therefor

An image forming apparatus capable of preventing the degradation of performance when the log data is outputted to an external device. An output unit outputs an operation condition about image forming as log data to an external device. A changing unit changes a detailed degree of the log data outputted by the output unit according to a log level that classifies the detailed degrees of the log data into some levels. A setting unit sets up a limit value corresponding to volume of the log data outputted by the output unit. A control unit controls the log level based on the limit value set up by the setting unit.