Provided is a pinhole inspecting method for suitably inspecting a pinhole in a bottle compared with conventional pinhole inspection. A reference inner pressure (P1) is a bottle inner pressure obtained directly after closing a supply valve (3) after opening the supply valve (3) for only a predetermined time. Whether the reference inner pressure (P1) is over a previously specified first threshold value (Pth1) or not is checked, and when it exceeds the first threshold value (Pth1), airtight status of the bottle is held for a predetermined time, and then a pressure reduction quantity (ΔP) of the bottle inner pressure from the reference inner pressure is measured after a fixed time. The bottle is judged to have no pinholes only when the value of ΔP is not exceeding the previously specified second threshold value (ΔPth2).