diff --git a/AUTHORS.TXT b/AUTHORS.TXT
index ca4088ad..2b49ec7b 100644
--- a/AUTHORS.TXT
+++ b/AUTHORS.TXT
@@ -1,5 +1,5 @@
 SoftEther VPN is developed by SoftEther VPN Project at University of Tsukuba.
-http://www.softether.org/
+https://www.softether.org/
 
 AUTHORS OF SOFTETHER VPN
 ------------------------
@@ -134,5 +134,5 @@ JOIN THE SOFTETHER VPN DEVELOPMENT
 Want to become a contributor? Please send us a patch.
 
 See also: SoftEther VPN Patch Acceptance Policy
-http://www.softether.org/5-download/src/9.patch
+https://www.softether.org/5-download/src/9.patch
 
diff --git a/src/BUILD_UNIX.md b/src/BUILD_UNIX.md
index b9554209..0519592c 100644
--- a/src/BUILD_UNIX.md
+++ b/src/BUILD_UNIX.md
@@ -137,9 +137,7 @@ vpncmd
 
 Or you can also use VPN Server Manager GUI Tool on other Windows PC to
 connect to the VPN Server remotely. You can download the GUI Tool
-from http://www.softether-download.com/.
-
-
+from https://www.softether-download.com/.
 
 
 ## Start/Stop SoftEther VPN Bridge
@@ -165,7 +163,7 @@ vpncmd
 
 Or you can also use VPN Server Manager GUI Tool on other Windows PC to
 connect to the VPN Bridge remotely. You can download the GUI Tool
-from http://www.softether-download.com/.
+from https://www.softether-download.com/.
 
 
 ## Start/Stop SoftEther VPN Client
@@ -191,7 +189,7 @@ vpncmd
 
 Or you can also use VPN Client Manager GUI Tool on other Windows PC to
 connect to the VPN Client remotely. You can download the GUI Tool
-from http://www.softether-download.com/.
+from https://www.softether-download.com/.
 
 
 # About HTML5-based Modern Admin Console and JSON-RPC API Suite
@@ -235,4 +233,4 @@ In this case please do not run the `make install` command after compiling the so
 ************************************
 Thank You Using SoftEther VPN !
 By SoftEther VPN Open-Source Project
-http://www.softether.org/
+https://www.softether.org/
diff --git a/src/BUILD_WINDOWS.md b/src/BUILD_WINDOWS.md
index 1ce328f8..ad0b13df 100644
--- a/src/BUILD_WINDOWS.md
+++ b/src/BUILD_WINDOWS.md
@@ -74,4 +74,4 @@ Download Links:
 ************************************
 Thank You Using SoftEther VPN !
 By SoftEther VPN Open-Source Project
-http://www.softether.org/
+https://www.softether.org/
diff --git a/src/WARNING.TXT b/src/WARNING.TXT
index 3fda535d..c61a4fda 100644
--- a/src/WARNING.TXT
+++ b/src/WARNING.TXT
@@ -332,7 +332,7 @@ VPN Gate Academic Experiment Project is an online service operated for just
 the academic research purpose at the graduate school of University of Tsukuba,
 Japan. The purpose of this research is to expend our knowledge about the
 "Global Distributed Public VPN Relay Server" (GDPVRS) technology. For details,
-please visit http://www.vpngate.net/.
+please visit https://www.vpngate.net/.
 
 5.2. About VPN Gate Service
 SoftEther VPN Server and SoftEther VPN Client may contain "VPN Gate Service"
@@ -468,7 +468,7 @@ Gate Service's user illegally abused your VPN Gate Service and you have to
 decode the packet logs in order to comply the laws), contact the administrator
 of the VPN Gate Academic Experiment Service at Graduate School of University
 of Tsukuba, Japan. You can find the contact address at
-http://www.vpngate.net/. The administrator of VPN Gate Service will respond to
+https://www.vpngate.net/. The administrator of VPN Gate Service will respond to
 decode the packet logs if there is an appropriate and legal request from court
 or other judicial authorities, according to laws.