To improve the acceleration length in laser plasma acceleration, we investigate the discharge plasma waveguide with a magnetic field. The discharge circuit consists of two pulsed-power circuits for preionization and main discharge. Discharges were repeated through the circuit using high-power semiconductor switches. Laser propagation characteristics of discharge plasma waveguide with the external magnetic field were observed. The results show that the reproducibility of waveguide with the external magnetic field is relatively high compared to that without magnetic field. The laser intensity gradually decreases with the strength of external magnetic field. These results suggest that the electron density profile is possible to control using the discharge plasma waveguide with an external magnetic field.