It was fifth trip by Ken Noguchi, who began his clean up campaign in the year 2000.
Now he thinks Everest is much cleaner than before because more people are aware of the impact of leaving garbage on the mountain.
"During this year's clean-up expedition, I found that the amount of waste left on the mountain has been drastically decreased," Noguchi told reporters on Monday.
Although estimates vary, some say there are 50 tons of trash on the mountain - left behind over 54 years of climbing since New Zealander Edmund Hillary and Sherpa Tenzing Norgay first conquered Everest on May 29, 1953.
The high altitude, deep snow, icy slopes and low level of oxygen make it difficult for climbers to carry anything other than the necessities down the mountain once they reach the peak.
As a result, Everest has been nicknamed the world's highest garbage dump. In recent years, however, the Nepalese government has tightened its laws, and climbers and their guides are now required to carry out gear - tents, ropes, sleeping bags, oxygen tanks - and trash or forfeit a US$4,000 (EUR2,970) deposit.
There have been several expeditions to clean up Everest in the past, but some have been accused of concentrating more on scaling the peak than on bringing down garbage.
The choice of the city of Helsinki is not incidental as the capital of Finland had hosted US-Soviet negotiations on the limitation of nuclear stockpiles in 1969