The figure marked a sharp slowdown from the 6.32-percent growth seen in February and 5.65 percent in March.
In the first four months of 2013, FDI inflow to China, which excludes those to the financial sector, grew 1.21 percent year on year to $38.34 billion, MOC spokesman Shen Danyang said at a press conference.
"We expect FDI to grow steadily this year," said Shen.
During the January-April period, China approved the establishment of 6,687 foreign-invested enterprises, down 4.69 percent from a year earlier.
The service sector saw a steady increase of FDI inflows in the first four months, up 6.87 percent year on year and accounting for 49.36 percent of the total FDI inflow during the period.
Foreign investment into China's manufacturing sector went down 3.83 percent, taking a 42.7 percent share in the FDI inflow, Shen said.
Lu Jinyong, a professor from Beijing's University of International Business and Economics, said as China moves up the value chain and focuses on brand building, the investment structure will become more optimized.
In breakdown, direct investment from the European Union and the United States jumped 29.68 percent and 33.2 percent, respectively, to $2.47 billion and $1.4 billion in the first four months.
Regionally, China's western areas saw strong growth in foreign investment, with an increase of 25.7 percent, compared with a 5.7-percent gain for the central regions and 1.1-percent drop for the east.