To provide a steel bar connecting device capable of securely fastening a plate-shaped member to a steel bar with nuts without reducing strength overall, while also preventing grout securing the steel bar to a cylindrical bolt from leaking and wasting.

In the steel bar connecting device for connecting the steel bar 2 to the plate-shaped member 6 with nuts 5a and 5b, the cylindrical bolt 1 has formed on its inside a steel bar hole 1a for inserting the steel bar 2 therein and has formed on its outside a threaded part 1b. A grout inlet 1c and outlet 1d which radially penetrate the bolt are bored through the bolt. The cylindrical bolt 1 is secured to the steel bar 2 with grout 4, is inserted into a hole 6a provided in the plate-shaped member 6, and is fastened with the nuts 5a and 5b.