Provided is a biological information detecting device including: a device main body (4) a heart rate detector (3a and 3b) that is integrally provided with the device main body (4) and includes an electrode (7a and 7b) and a fixing band (80) for mounting the device main body (4) and the heart rate detectors (3a and 3b) on a user, the fixing band (80) being formed of an extendable band-shaped member, in which the fixing band (80) includes adjusting portions (30) that are able to adjust an effective length of the fixing band (80), and the adjusting portions (30) include a first adjusting portion (50) and a second adjusting portion (60) that roughly and finely adjust the effective length of the fixing band (80), respectively, such that the device main body (4) and the heart rate detectors (3a and 3b) can be mounted on the user.
