The number of criminal cases in the first half of this year hit a record 1,351,727, up 4.9 percent from a year earlier, the National Police Agency said Thursday.
The overall arrest rate grew to 20.1 percent, up 1.1 percentage points from the previous year, when it was at a record low.
While the number of serious crimes, including murder and robbery, increased by 3.5 percent to 9,715, the arrest rate fell 1.9 percentage points to a record-low 52.5 percent.
"We have made improvements in tackling light crimes such as bag-snatching, but we are still struggling to prevent the expansion of crimes (in general)," the NPA said.
The number of youth criminal offenders grew by 6.8 percent to 65,573.
People aged between 14 and 19 accounted for 70 percent of all bag-snatchings and muggings.
"Juvenile delinquents have made Japanese streets dangerous," an NPA official said.
The number of crimes involving youths grew 1.9 percent to 185,357.
There were 1,135,858 theft cases, accounting for 84 percent of overall criminal acts.
The number of investigated violent crimes resulting from domestic violence, including murder, grew 21.1 percent to 785.
Cases of counterfeiting skyrocketed 208.7 percent to 2,118.
Crimes involving non-Japanese people grew 33 percent to 10,631. Chinese nationals accounted for 44.6 percent of such cases.