Crowdsourcing is becoming increasingly popular in various tasks. Although the cost incurred by workers in crowdsourcing is lower than that by experts, the possibility of errors in the former generally exceeds that of the latter. One of the important approaches to quality control of crowdsourcing is based on mechanism design, which has been used to design a game’s rules/protocols so that agents have incentives to truthfully declare their preferences, and designers can select socially advantageous outcomes. Thus far, mechanism design has been conducted by professional economists or computer scientists. However, it is difficult to recruit professional mechanism designers, and developed mechanisms tend to be difficult for people to understand. Crowdsourcing requesters have to determine how to assign tasks to workers and how to reward them. Therefore, a requester can be considered to be an “amateur mechanism designer”. This paper introduces the “wisdom of the crowd” approach to mechanism design, i.e., using crowdsourcing to explore the large design space of incentive mechanisms. We conducted experiments to show that crowd mechanism designers can develop sufficiently diverse candidates for incentive mechanisms and they can choose appropriate mechanisms given a set of candidate mechanisms. We also studied how the designers’ theoretical, economic, and social tendencies, as well as their views on the world, justifiably affect the mechanisms they propose.