A mounting substrate on which at least any one of three kinds of electronic components including a first electronic component, a second electronic component, and a third electronic component are able to be mounted includes a pair of first edge portions and a pair of second edge portions. When a dimension of the first electronic component in its length direction is designated as L1, a dimension of the first electronic component in its width direction is designated as W1, a dimension of the second electronic component in its length direction is designated as L2, and a dimension of the second electronic component in its width direction is designated as W2, a dimension of the third electronic component in its width direction is any one of W1 and W2, and a dimension of the third electronic component in its length direction is L2 when the dimension of the third electronic component in its width direction is W1, and is L1 when the dimension of the third electronic component in its width direction is W2. At least one or more of the third electronic components are mounted on the mounting substrate.