Vagrant upができない！！

virtualboxとvagrantを用いてローカル環境構築をしようとしている際、両者をインストールし終えた後、vagrantのboxを追加し、initで初期化した後、　vagrant upをコマンドした際に次のようなエラーが起きてしましました。

ちなみにvirtualboxのバージョンは6.1.2で、vagrantのバージョンは2.2.6でした。

No usable default provider could be found for your system.

Vagrant relies on interactions with 3rd party systems, known as
"providers", to provide Vagrant with resources to run development
environments. Examples are VirtualBox, VMware, Hyper-V.

The easiest solution to this message is to install VirtualBox, which
is available for free on all major platforms.

If you believe you already have a provider available, make sure it
is properly installed and configured. You can see more details about
why a particular provider isn't working by forcing usage with
vagrant up --provider=PROVIDER, which should give you a more specific
error message for that particular provider.

この解決策を教えていただきたいです！

vagrantfileはデフォルトのままで以下の通りです。↓

vagrantfile
1# -*- mode: ruby -*-
2# vi: set ft=ruby :
3
4# All Vagrant configuration is done below. The "2" in Vagrant.configure
5# configures the configuration version (we support older styles for
6# backwards compatibility). Please don't change it unless you know what
7# you're doing.
8Vagrant.configure("2") do |config|
9  # The most common configuration options are documented and commented below.
10  # For a complete reference, please see the online documentation at
11  # https://docs.vagrantup.com.
12
13  # Every Vagrant development environment requires a box. You can search for
14  # boxes at https://vagrantcloud.com/search.
15  config.vm.box = "centos/7"
16
17  # Disable automatic box update checking. If you disable this, then
18  # boxes will only be checked for updates when the user runs
19  # `vagrant box outdated`. This is not recommended.
20  # config.vm.box_check_update = false
21
22  # Create a forwarded port mapping which allows access to a specific port
23  # within the machine from a port on the host machine. In the example below,
24  # accessing "localhost:8080" will access port 80 on the guest machine.
25  # NOTE: This will enable public access to the opened port
26  # config.vm.network "forwarded_port", guest: 80, host: 8080
27
28  # Create a forwarded port mapping which allows access to a specific port
29  # within the machine from a port on the host machine and only allow access
30  # via 127.0.0.1 to disable public access
31  # config.vm.network "forwarded_port", guest: 80, host: 8080, host_ip: "127.0.0.1"
32
33  # Create a private network, which allows host-only access to the machine
34  # using a specific IP.
35  # config.vm.network "private_network", ip: "192.168.33.10"
36
37  # Create a public network, which generally matched to bridged network.
38  # Bridged networks make the machine appear as another physical device on
39  # your network.
40  # config.vm.network "public_network"
41
42  # Share an additional folder to the guest VM. The first argument is
43  # the path on the host to the actual folder. The second argument is
44  # the path on the guest to mount the folder. And the optional third
45  # argument is a set of non-required options.
46  # config.vm.synced_folder "../data", "/vagrant_data"
47
48  # Provider-specific configuration so you can fine-tune various
49  # backing providers for Vagrant. These expose provider-specific options.
50  # Example for VirtualBox:
51  #
52  # config.vm.provider "virtualbox" do |vb|
53  #   # Display the VirtualBox GUI when booting the machine
54  #   vb.gui = true
55  #
56  #   # Customize the amount of memory on the VM:
57  #   vb.memory = "1024"
58  # end
59  #
60  # View the documentation for the provider you are using for more
61  # information on available options.
62
63  # Enable provisioning with a shell script. Additional provisioners such as
64  # Puppet, Chef, Ansible, Salt, and Docker are also available. Please see the
65  # documentation for more information about their specific syntax and use.
66  # config.vm.provision "shell", inline: <<-SHELL
67  #   apt-get update
68  #   apt-get install -y apache2
69  # SHELL
70end