Gap measurement device for combustor, and gap measurement method

The purpose of the present invention is to provide a gap measurement device (20) for a combustor (1) and a gap measurement method, with which the size of a gap between a first cylindrical body (2a) surrounding the periphery of a combustion nozzle, and a second cylindrical body (2b) which is connected to the first cylindrical body (2a) and which guides combustion gas to a down-stream side, can be measured when the combustor (1) is in an assembled state. This gap measurement device (20) for the combustor (1) is provided with: a rod member (30) which, in a state of being inserted inside the combustor (1), is attached to a first flange (1a) of the combustor (1), at least a base-end side of said rod member (30) being hollow; a support member (50) attached to a tip of the rod member (30) so as to be capable of rotating about a shaft core (55) orthogonal to the axial direction of the rod member (30); an imaging element (60) which is supported on the support member (50), and which images an annular gap (19); an operation lever (70) which passes through the inside of the rod member (30), and which extends towards the support member (50); and a link mechanism (80) which is provided between the operation lever (70) and the support member (50), and which converts back-and-forth movement of the operation lever (70) into rotational movement of the support member about the shaft core (55).