A band-pass filter device includes a waveguide filter, a first circuit board section, a first antenna, a second circuit board section, and a second antenna. The waveguide filter includes a high-pass portion, a connection portion, and a low-pass portion. The first antenna is disposed on the first circuit board section. The second antenna is disposed on the second circuit board section. A wireless signal generated by the first antenna is transmitted through the high-pass portion, the connection portion, and the low-pass portion of the waveguide filter, and then is received by the second antenna.