An object of the present invention is to provide a pyrroloquinoline quinone tetraalkali salt needing no special reagent, having a high solubility in a solvent, being capable of providing a high-concentration pyrroloquinoline quinone aqueous solution, being hardly changed in color even if being concurrently used with ascorbic acid, and being of a high quality and a high purity； a crystal of a pyrroloquinoline quinone tetrasodium salt； a composition； and a simple method for producing the pyrroloquinoline quinone tetraalkali salt. The pyrroloquinoline quinone tetraalkali salt is represented by the formula (1): wherein M is each independently one selected from the group consisting of Li, K, Na, Rb and Cs.
