Stellar tidal disruption events (TDEs) by supermassive black holes are now discovered at a rate of about a dozen annually from optical time-domain surveys. However, they are puzzlingly overrepresented in post-starburst galaxies but almost absent in normal star-forming galaxies. We report an energetic mid-infrared nuclear outburst in a nearby Milky Way-sized star-forming galaxy SDSSJ0103+1401, which did not show any signatures of active galactic nucleus prior to the outburst. The infrared outburst can be perfectly fitted by a dust echo model of an optical-UV transient on time scale of half a year with its total radiant energy in the infrared exceeding known supernovae. Along with many other analogs, we suggest that there exists a new population of dust obscured TDEs in star-forming galaxies, represented by SDSSJ0103+1401, missed by previous optical or soft X-ray surveys, but can be efficiently uncovered by their IR echoes. The puzzle of post-starburst preference could be highly alleviated with the obscured population taken into consideration.