A modular camera structure to be mounted on the rear-view mirror frame on either lateral side of a large vehicle to eliminate rear-view blind spots includes an annular base, a cover, and a fastening member. The annular base has an annular projection on which an image-recording device is placed, and a curved groove on the opposite side. The cover has a lower opening coupled with the annular projection such that the image-recording device is secured in the cover and has its lens exposed through an upper opening of the cover. A recessed portion of the fastening member and the curved groove of the annular base can engage with two opposite sides of the rear-view mirror frame respectively, before locking members lock two ends of the fastening member to the annular base to secure the annular base and the fastening member tightly to the rear-view mirror frame in a clamping manner.