We collected information on the functional traits of the macrobenthos that inhabit mainly tidal flats along the Northwest Pacific coast of Tohoku, Japan, based on the species that were present during a survey after the Great East Japan Earthquake of 2011. The dataset contains information on 33 traits of 246 species and includes their taxonomic position, distribution, body length, habitat, reproduction type, and other characteristics such as diet type, migratory type, and invasiveness. Information about most basic traits such as body length, distribution, and habitat characteristics is complete, and more than 50% of trait information is complete for over 100 species, but information about reproduction is relatively limited. Although we did not limit our study to specific taxa and even included vegetation in the database, the majority of the taxa are Arthropoda, Mollusca, and Annelida. This file also has a table that compares the traits data to the existing traits database BIOTIC (Biological Traits Information Catalogue) to facilitate transformation and reuse of the data. Because the area of this survey was very adversely impacted by the Great East Japan Earthquake and Tsunami of 11 March 2011 and by post-disaster anthropogenic activities, this database will be relevant to assessments of post-disaster changes of the benthic community due to both the tsunami and human activities. The database is expected to fill the gap between the identification of species and assessments of community composition.