The present invention relates to a substrate unit and a substrate assembly, and a camera module using the same. The present invention may comprise: a first substrate part having rigidity; a second substrate part stacked on one surface of the first substrate part and having flexibility; a third substrate part extending outwardly from the second substrate part and having flexibility; and a reinforcing part which is disposed at a portion where the edge portions of the first substrate part and the third substrate part meet, the reinforcing part having a recessed portion which is formed by recessing the first substrate part inwardly so as to inhibit interference between the first substrate part and the third substrate part. The present invention is capable of resolving the interference between a rigid PCB and a flexible PCB and the tearing thereof by providing a reinforcing part in a connection portion of the rigid PCB and the flexible PCB.