Object:It is desirable to provide a waterproof connection structure, a connection structure body, and a partition member that can easily and reliably prevent water penetration.Resolution Means:The waterproof connecting portion (1A) of a connection structure body (1) includes an FFC (30) formed by sandwiching a plurality of flat conductors (41) arranged in parallel in a width direction in a sheet-like insulating covering, a plurality of insulated wires (40) each obtained by covering a conductor (41) with an insulating covering (42), a plurality of WF terminals (20) that are arranged in parallel in the width direction and connect the flat conductors (41) and the conductors (41), a terminal holder (10) that partitions the WF terminals (20) in an insulating manner, and a butyl sheet (50) that integrally covers the plurality of WF terminals (20) partitioned by the terminal holder (10) and the terminal holder (10), and has waterproofing properties, insulating properties, and stretching properties.