A mountingdemounting construction relates to a mountingdemounting construction of a heavy unit and so on, and can heighten safety of mounting and demounting thereof. Electrodes are arranged on a principal surface of the first substrate, and pillar-shaped terminals are bonded to the respective electrodes with solder portions provided therebetween. Adjacent contacts of the first set have a first spacing, and adjacent contacts of the second set have a second spacing different from the first spacing.