  Designing a financial market that works well is very important for developing
and maintaining an advanced economy, but is not easy because changing detailed
rules, even ones that seem trivial, sometimes causes unexpected large impacts
and side effects. A computer simulation using an agent-based model can directly
treat and clearly explain such complex systems where micro processes and macro
phenomena interact. Many effective agent-based models investigating human
behavior have already been developed. Recently, an artificial market model,
which is an agent-based model for a financial market, has started to contribute
to discussions on rules and regulations of actual financial markets. I
introduce an artificial market model to design financial markets that work well
and describe a previous study investigating tick size reduction. I hope that
more artificial market models will contribute to designing financial markets
that work well to further develop and maintain advanced economies.
