A touch detection device includes: a first sensor having a first capacitance; a monitoring unit configured to monitor the first capacitance of the first sensor at a first period; a determining unit configured to determine whether the first capacitance monitored by the monitoring unit exceeds a first threshold; and a period changing unit configured to change the first period into a second period that is shorter than the first period when the determining unit determines that the first capacitance exceeds the first threshold.