In a reflow soldering apparatus, when changing the operation mode from a production mode to a temperature profile mode, a warning-issue-time is set to a point of time (for example, several seconds) before the circuit board reaches an exit of the main body of the soldering apparatus to issue an alarm at this set time. A control unit thereof calculates a period of time when the alarm issues based on the set warning-issue-time before circuit-board-discharge and the like. After a sensor of entrance side has detected that the circuit board enters into main body of the reflow soldering apparatus, the control unit determines whether or not the starting time of the alarm sound has been elapsed. The control unit controls the information unit to sound the alarm when the control unit determines that the starting time of the warning issue has elapsed.