According to one embodiment, a module connection structure designed to connect a module to other modules. The module includes a dielectric layer, a micro-strip path, a projection, and a plurality of gain adjusting lands. The dielectric layer is formed on a substrate. The micro-strip path is provided on the dielectric layer and configured to transmit a transmission signal input to one end portion, to the other end portion. The projection is formed at edges of the substrate, which are adjacent to the other modules, and protruding from the micro-strip path and the dielectric layer toward the other modules. The plurality of gain adjusting lands is formed adjacent to the micro-strip path, for use in adjusting an input/output gain of the module. The gain adjusting lands uncouple from the micro-strip path or other gain adjusting lands couple to the micro-strip path, thereby to adjust the input/output gain of the module.