We present distance measurement of the semiregular variable RX Bootis ( RX Boo ) with its annual parallax .
Using the unique dual-beam system of the VLBI Exploration of Radio Astrometry ( VERA ) telescope , we conducted astrometric observations of a water maser spot accompanying RX Boo referred to the quasar J1419+2706 separated by 1 ^ { \circ } .69 from RX Boo .
We have measured the annual parallax of RX Boo to be 7.31 \pm 0.50 mas , corresponding to a distance of 136 ^ { +10 } _ { -9 } pc , from the one-year monitoring observation data of one maser spot at V _ { { LSR } } = 3.2 { km s } ^ { -1 } .
The distance itself is consistent with the one obtained with Hipparcos .
The distance uncertainty is reduced by a factor of two , allowing us to determine the stellar properties more accurately .
Using our distance , we discuss the location of RX Boo in various sequences of Period-Luminosity ( PL ) relations .
We found RX Boo is located in the Mira sequence of PL relation .
In addition , we calculated the radius of photosphere and the mass limitation of RX Boo and discussed its evolutionary status .