A method of manufacturing a combined circuit board includes the following steps. First, through portions (TPs) arranged in a predetermined format are formed in a rigid substrate (RS) such that the RS is divided into a predetermined removed region (PRR1) and a predetermined reserved region (PRR2) according to the arrangement of the TPs. Next, a conductive bonding layer (CBL) and a flexible circuit board (FCB) are respectively laminated on two opposite sides of the RS and part of a dielectric bonding layer of the CBL fills the TPs. Next, the RS, the FCB and the CBL are bent according to the TPs such that the PRR2 is bent at the TPs relative to the PRR1. Finally, part of the RS located at the PRR1 and part of the CBL corresponding to the PRR1 are removed to form an indentation to expose part of the FCB.