Market server and power trading system

A power trading system comprising:

• a market server of a power trading market;
• and
• an agent device used by each of participants of the power trading market, wherein
• the market server has a memory that stores participant information of the participant,
• the participant information includes
• a participant ID that specifies the participant, and
• participant evaluation information associated with the participant ID and set based on a trading history of the participant, and
• when the participant evaluation information satisfies a predetermined condition, the market server permits the participant specified by the participant ID associated with the participant evaluation information to participate in the power trading market.