NOVELTY - A joining film transfer sheet (1a) has a joining film (3,33) provided on one surface of a base material (2a). The base material and joining film have peelability. The joining film contains leaving group consisting of organic group, and is coupled with silicon structure having atomic structure including siloxane coupling. Energy is provided to region (32) of at least one portion of joining film, leaving group is desorbed, adhesiveness expressed on joining film is utilized, and joining film is joined on to-be-adhered component (5a) and peeled in an interface with base material.    USE - Joining film transfer sheet for joining to-be-adhered components and forming joined component (claimed). Uses include but are not limited to transistor, diode, memory, quartz oscillator, reflective mirror, optical lens, diffraction grating, optical filter, photoelectric conversion element e.g. solar cell, inkjet type recording head, etc.    ADVANTAGE - The joining film transfer sheet easily and efficiently enables to join to-be-adhered components. The joining film is reliably transferred.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for joining method, which involves providing energy to surface of joining film of transfer sheet, disconnecting leaving group from silicon structure, expressing adhesiveness, laminating transfer sheet and to-be-adhered component such that surface of to-be-adhered component and joining film are contacted, obtaining temporary joined component (7), peeling base material from temporary joined component (7), transferring joining film to to-be-adhered component, obtaining temporary joined component (B), disconnecting leaving group from silicon structure, expressing adhesiveness, laminating temporary joined component (B) and other to-be-adhered component, such that peeling surface of joining film and other to-be-adhered component are contacted, and obtaining joined component.    DESCRIPTION OF DRAWING(S) - The drawing shows the longitudinal cross-sectional view of joining film transfer sheet.    Joining film transfer sheet (1a)    Base material (2a)    Joining film (3,33)    To-be-adhered component (5a)    Temporary joined component (7)    Region (32)    Convex portion (51)