A surroundings monitoring apparatus comprising: an obtaining portion obtaining a first captured image data outputted by a first image capturing portion (16a, 16c) and a second captured image data outputted by a second image capturing portion (16b, 16d), the first image capturing portion (16a, 16c) being provided at a vehicle and capturing an image in a traveling direction of the vehicle and the second image capturing portion (16b, 16d) being provided at the vehicle and capturing an image in a width direction of the vehicle, the traveling direction of the vehicle corresponding to a first image capture region and the width direction of the vehicle corresponding to a second image capture region; and an output portion superimposingly displaying an indicator (Pa, Qa), which indicates a predetermined region relative to the vehicle, in at least one of a first display region displaying an image which is based on the first captured image data and a second display region (SVL, SVR) displaying an image which is based on the second captured image data, a region in which the indicator (Pa, Qa) is superimposedly displayed corresponding to a superimposed region of the indicator (Pa, Qa), in a case where the superimposed region of the indicator (Pa, Qa) is included in the other of the first display region and the second display region (SVL, SVR), the output portion superimposingly displaying the indicator (Pa, Qa) in the other of the first display region and the second display region (SVL, SVR) in a display manner which corresponds to a display manner of the indicator (Pa, Qa) displayed in the one of the first display region and the second display region (SVL, SVR), wherein the output portion displays reference lines (Pa, Qa) as the indicator (Pa, Qa), wherein the reference line (Pa), which is apart from a corresponding side surface of the vehicle by the predetermined distance, is displayed in the second display region (SVL, SVR) and a part of the reference line (Pa) displayed in the second display region (SVL, SVR) is displayed in the first display region, characterized in that the reference line (Qa), which is apart from the front bumper of the vehicle by the predetermined distance, is displayed in the first display region and a part of the reference line (Qa) displayed in the first display region is displayed in the second display region (SVL, SVR). an obtaining portion obtaining a first captured image data outputted by a first image capturing portion (16a, 16c) and a second captured image data outputted by a second image capturing portion (16b, 16d), the first image capturing portion (16a, 16c) being provided at a vehicle and capturing an image in a traveling direction of the vehicle and the second image capturing portion (16b, 16d) being provided at the vehicle and capturing an image in a width direction of the vehicle, the traveling direction of the vehicle corresponding to a first image capture region and the width direction of the vehicle corresponding to a second image capture region; and an output portion superimposingly displaying an indicator (Pa, Qa), which indicates a predetermined region relative to the vehicle, in at least one of a first display region displaying an image which is based on the first captured image data and a second display region (SVL, SVR) displaying an image which is based on the second captured image data, a region in which the indicator (Pa, Qa) is superimposedly displayed corresponding to a superimposed region of the indicator (Pa, Qa), in a case where the superimposed region of the indicator (Pa, Qa) is included in the other of the first display region and the second display region (SVL, SVR), the output portion superimposingly displaying the indicator (Pa, Qa) in the other of the first display region and the second display region (SVL, SVR) in a display manner which corresponds to a display manner of the indicator (Pa, Qa) displayed in the one of the first display region and the second display region (SVL, SVR), wherein the output portion displays reference lines (Pa, Qa) as the indicator (Pa, Qa), wherein the reference line (Pa), which is apart from a corresponding side surface of the vehicle by the predetermined distance, is displayed in the second display region (SVL, SVR) and a part of the reference line (Pa) displayed in the second display region (SVL, SVR) is displayed in the first display region, characterized in that the reference line (Qa), which is apart from the front bumper of the vehicle by the predetermined distance, is displayed in the first display region and a part of the reference line (Qa) displayed in the first display region is displayed in the second display region (SVL, SVR).