Abstract: A tire pressure monitoring device includes a housing unit, a tire inflating unit, and a tire pressure monitoring unit. The housing unit includes: a tubular body confining an air chamber; a tire coupling seat adapted to couple the tubular body to a tire such that the air chamber is in fluid communication with an interior of the tire; and a cap body formed with an outwardly extending annular flange to engage a retainer part of the tubular body. The tire inflating unit includes an inflating tube connected at one end to the tubular body and in fluid communication with the air chamber, and an inflating valve. The tire pressure monitoring unit is disposed in the tubular body and is covered by the cap body.