To acquire an object detection apparatus capable of facilitating the cleaning of a container, preventing the occurrence of operational failure, preventing a solution from overflowing from the container, and detecting the mounting of the container to a correct position.

The object detection apparatus is provided with the container 20 freely detachably mounted on a main body 30 for storing a liquid 40 and a sensor 1 mounted on the main body 30 for measuring the distance to an opposite object on the basis of reflection signals from the opposite object. Reflection signals 70 from the opposite object when the container 20 is at a normal mounting position of the main body 30 and reflection signals 70 when the container 20 is not at a normal mounting position are made different from each other. In this case, the distance from the sensor 1 to the position of the bottom surface 20b of the container 20 opposite to the sensor 1 is made different depending on whether the the container 20 is at the normal mounting position or not.