Provided is a composite particle which can improve the capacity per volume and charge-discharge cycle characteristics. The composite particle includes a plurality of specific particles and a binding material. The specific particle contains an alloy phase. The alloy phase undergoes thermoelastic diffusionless transformation when releasing metal ions or occluding metal ions. The binding material contains at least one of non-graphite carbon and a carbon precursor. The plurality of specific particles bind with each other via the binding material.