A biological information detection device is installed in equipment including a body support portion, and detects biological information of a user of the equipment. The device includes: a detection unit including: a transmitter which transmits a radio wave toward a part of the body supported by the body support portion; and a receiver which receives a reflected wave obtained as the radio wave transmitted by the transmitter and then reflected on a part of the body; and a detection support portion which forms a part of the body support portion, and which supports a part of the body to which thetransmitter transmits the radio wave. Hardness with respect to a part of the body at the detection support portion is softer than hardness with respect to a part of the body at the body support portion excluding the detection support portion.