1The manager of a "section" (課) within a company or government office — a middle-management position, above 係長 (kakarichō) and below 部長 (buchō).
来月、彼は課長に昇進することになった。
Next month, he's going to be promoted to section manager.
課長は毎朝、部下全員に仕事を割り振る。
The section manager assigns tasks to all his subordinates every morning.
その件については課長に相談したほうがいい。
You should consult the section manager about that matter.