The conglomerate, whose products range from diggers to nuclear reactors, said it earned 20.2 billion yen ($217.8 million) in its third quarter to December, down from 34.2 billion yen a year earlier.
Sales slipped seven percent to 2.11 trillion yen, it said.
For the nine months to December, Hitachi said net profit was down to 50.3 billion yen from 85.1 billion yen a year earlier.
The company slashed its full-year to March net profit estimate by 50 billion yen to 150 billion yen on 8.9 trillion yen in revenue.
Weakness in the construction equipment unit was largely due to "lower sales of hydraulic excavators due to the impact of lower demand in China", it said, as concerns remain over the strength of the world's second-biggest economy.
But Hitachi said its power systems unit as well as social infrastructure and industrial systems division, which includes its elevator and escalator business, both saw a boost in sales.
In October, Hitachi said it would buy British atomic power venture Horizon to expand its nuclear business overseas, as the Japanese remain wary about atomic power after the Fukushima disaster in 2011.
The purchase price was 696 million pounds ($1.09 billion).
Horizon planned to build two or three 1,300-megawatt-class reactors at each of two nuclear power stations in Britain and Hitachi will take over the task, the Japanese company said at the time.