To reduce the quantity of knowledge that a person in charge of business should have.

A business supporting device 1 for supporting the business of a plurality of types of building is provided with a means for storing construction plan sheet information 10 for storing constructing plan information associated with each type of building configured on the basis of specifications preliminarily set to determine the whole part or most part of the costs of the building main body construction, and for storing item explanation information for explaining the contents of the whole part or one part of items of the construction plan information. Furthermore, the business supporting device 1 is provided with a construction plan sheet preparing means 15 having a building type selecting means for selecting any type of the above buildings, a sheet display means for displaying the construction plan sheet of the selected type of building on the basis of the constructing plan information, and an explanation display means for displaying the explanations associated with an item included in the constructing plan sheet designated by a predetermined operation on the basis of the item explanation information.