Mogstad was general handyman on the first Fram expedition.

Ivar Otto Irgens Mogstad was born in Aure, Nordmøre county as the youngest of six siblings. His father was a teacher and church singer. Ivar took the exam as a forest worker in 1877 and from 1882 he was a head guard at the Gaustad psychiatric hospital in Oslo.

Mogstad was engaged on the Fram as a general crew member and Nansen wrote that he made himself useful on board in all ways, from watchmaker to dog watcher. His references showed that he was particularly interested and experienced in technical matters. On board he also worked as hunter, stoker and carpenter, and he entertained on the violin. He was apparently quite an inventor, with several patents to his name.

Several of those on board reported that he was good at starting quarrels and dramas, which could end in a fist fight. In his diary he wrote that he dreamt a lot during the expedition.

After the expedition Mogstad worked as an alcohol inspector. He was fond of hunting and he built a small cabin in Nordmøre where he hunted bears. One of his bears is exhibited in the Academy of Sciences in Trondheim. He remained unmarried until he died in Trondheim in 1928. The money he had saved he donated to the development of forestry in Aure