A vehicle-mounted device, mounted on a vehicle, providing a processor and storage device to execute a program (119, 120,121), stored in the storage device, by the processor, further comprising: an interrupt and restart detecting unit configured to acquire a vehicle condition including a brake pedal condition, a vehicle speed and a parking brake condition from a vehicle condition acquisition means and to acquire the conditions of a power source from a power source interface; and characterized by an update processing means being configured - to continue an update processing of the program (119, 120, 121) when a current vehicle condition, being acquired by said interrupt and restart detecting unit, dissatisfies a predetermined update processing interrupt condition, and - to interrupt the update processing of the program when the current vehicle condition, having been acquired by said interrupt and restart detecting unit, satisfies the update processing interrupt condition, wherein the update processing interrupt condition is that the vehicle speed is zero and the brake pedal is being actuated, the update processing interrupt condition is that the parking brake is being actuated and the brake pedal is being actuated, or the update processing interrupt condition is that the power source condition is either in an ACC_OFF state or in an ACC_ON state and the brake pedal is being actuated; and wherein the state ACC_ON is a state in which the engine on the vehicle stops and power is supplied to the vehicle-mounted device, and the state ACC_OFF is a state in which the engine stops and power is not supplied to the vehicle-mounted device. an interrupt and restart detecting unit configured to acquire a vehicle condition including a brake pedal condition, a vehicle speed and a parking brake condition from a vehicle condition acquisition means and to acquire the conditions of a power source from a power source interface; and characterized by an update processing means being configured - to continue an update processing of the program (119, 120, 121) when a current vehicle condition, being acquired by said interrupt and restart detecting unit, dissatisfies a predetermined update processing interrupt condition, and - to interrupt the update processing of the program when the current vehicle condition, having been acquired by said interrupt and restart detecting unit, satisfies the update processing interrupt condition, - to continue an update processing of the program (119, 120, 121) when a current vehicle condition, being acquired by said interrupt and restart detecting unit, dissatisfies a predetermined update processing interrupt condition, and - to interrupt the update processing of the program when the current vehicle condition, having been acquired by said interrupt and restart detecting unit, satisfies the update processing interrupt condition, wherein the update processing interrupt condition is that the vehicle speed is zero and the brake pedal is being actuated, the update processing interrupt condition is that the parking brake is being actuated and the brake pedal is being actuated, or the update processing interrupt condition is that the power source condition is either in an ACC_OFF state or in an ACC_ON state and the brake pedal is being actuated; the update processing interrupt condition is that the vehicle speed is zero and the brake pedal is being actuated, the update processing interrupt condition is that the parking brake is being actuated and the brake pedal is being actuated, or the update processing interrupt condition is that the power source condition is either in an ACC_OFF state or in an ACC_ON state and the brake pedal is being actuated; and wherein the state ACC_ON is a state in which the engine on the vehicle stops and power is supplied to the vehicle-mounted device, and the state ACC_OFF is a state in which the engine stops and power is not supplied to the vehicle-mounted device.