A distributed system is provided that includes member nodes and a leader node. Each member node stores a database and updates the database by performing common ones of a plurality of transactions. The leader node generates a batch, to be executed by each member node, which includes two or more transactions lacking an access conflict from among the plurality of transactions. The leader node includes: a section that generates an access set as a set of database entries to be accessed by each transaction to be executed; a section that generates the batch, based on the access set of each transaction to be executed; and a leader-side section that performs a consensus process for the batch among the leader and member nodes. Each member node includes the database; a member-side section that performs a consensus process for the batch; and a section that performs parallel execution of batch transactions.